# Cool Math Tricks To Amaze Your Friends

Cool Math Trick Using 1

Math is like magic, except better! Here is a collection of cool math tricks you can learn to amaze your friends and learn more about how numbers work.

The 11 Rule

Everyone knows the “10 Rule” where you multiply by 10 simply by adding a 0 to the end of a number, but you might not know the 11 rule. This rule works for any two digit number to multiply it by 11:

For an example, let’s use the number 62

• Separate the two digits in your mind (6 __ 2).
• Add together the two digits of the numbers. (6 + 2 = 8).
• Place this number in the space or hole between the two digits (6 8 2).
• That’s it! 11 x 62 = 682

The only tricky part to remember is that if adding the two digits results in a number greater than 9, then you put the “ones” digit in the space and carry the “tens” digit. For example:

11 x 57 … 5 __ 7 … 5 + 7 = 12

so you put the 2 in the space and add the 1 to the 5, giving you the number 627

11 x 57 = 627

Countdown Math Trick

### Single Digit Numbers Math Trick

1. Think of 2 single digit numbers.
2. Take either of the numbers and double it.
3. Add 5 to the result.
5. Subtract 25 from the answer.
6. You’ll get the 2 single digit numbers in the answer.

### Using Shoe Size To Tell Your Age – Algebra Trick

There are many math tricks that ask you to supply a number to get a “hidden” number that you actually supply in a different form during the trick. The first number isn’t too important, since it gets removed during the trick, so you can change the wording of this math trick.

1. Use your shoe size to tell your age. Take your shoe size (whole number, so round up if it’s a half size).
2. Multiply it by 5.
4. Multiply it by 20.
5. Add 1016. (if you’re doing the trick in the year 2016… if it’s 2017 use 1017, in 2018 use 1018, etc.)
6. Subtract the year you were born.
7. The first digit is your shoe size and the last 2 digits are your age.

As you might guess, this trick is meant to reveal a number that is less than 100. The trick uses algebra to solve for the answer. Let’s do the trick again using s for shoe size and b for birth year:

Multiply s x 5: 5s

Multiply by 20: 20(5s + 50) = 100s + 1000

Add 1016 (depending on current year): 100s + 1000 + 1016 = 100s + 2016

Subtract birth year: 100s + 2016 – b

Why does it work (and why does it sometimes fail)? No matter what your shoes size is, it will be the first two digits of the answer. If your shoe size is 9, the 100s is 900. If you use a European size chart and wear a size 36, then 100s = 3600.

The age part takes the current year minus your birth year. The trick does not take into account your birth month, so if your birthday this year has not arrived, the answer will be a year off!

### 1, 2, 4, 5, 7, 8 Math Trick

1. Choose a number between 1 and 6.
2. Multiply the number by 9.
3. Multiply the result by 111.
4. Multiply the answer by 1001.
5. Divide the number by 7.
6. The answer will contains all the numbers 1, 2, 4, 5, 7, 8.

### The 1089 Math Trick

1. Think of a 3 digit number.
2. Arrange the digits in descending order.
3. Reverse the order and subtract it from the number in step 2.
4. Reverse the order of the answer.
5. Add it to the result from step 3. You get 1089!
• For example, let’s say I chose 423.
• Arrange in descending order: 432
• Reverse the order and subtract it from the previous number: 234… 432 – 234 = 198
• Reverse the order: 891
• Add the numbers together: 198 + 891 = 1089

1. Think of a number.
2. Double it.
4. Divide it by 2.

### Three Digits the Same Trick

1. Think of a 3 digit number where all the digits are the same  (e.g., 333, 777).

Cheryl’s Birthday Math Riddle

### How To Solve Cheryl’s Birthday Math Riddle

“Cheryl’s Birthday” is more of a math riddle or logic puzzle that is solved using the process of elimination or deductive reasoning. Albert can’t know the birthday because he only has the month and all months have multiple dates, but he has enough information to know Bernard does not have the date. If Cheryl had told Bernard 19 or 18, then he would know the whole birthday because there is only one month with each number. This rules out May 19 and June 18.

Since Albert knows Bernard doesn’t know, Albert must have been told July or August, as this rules out any possibility of Bernard being told 18 or 19. This excludes any dates in May or June.

When Bernard says he did not know the answer, but now he does, this means Bernard has the one remaining unique number in the list. If Bernard had a 14, he wouldn’t know whether it was in July or August. If he had a 15 or a 17, he wouldn’t know which date in August was correct. Thus Cheryl’s birthday must be July 16!

If you want to get really tricky, you can rephrase the riddle to say Bernard starts out saying he doesn’t know when the birthday is, with Albert replying he doesn’t know either. If Bernard then says he didn’t know, but now he does, and Albert replies he now knows too, then the answer is August 17. Can you see why?

Do you have other cool math tricks to add? Post a reply and share them!

# Physics Jokes

“Physics is Phun!” is what young physics students are told. You get to play with cool toys and call it ‘lab’. All you have to do is love playing with math too.

In the spirit of “Phun” here are a few physics jokes and puns.

Chemistry jokes are funny periodically, but physics jokes have more potential.

Physics is the science where it takes long, complicated equations to explain why round balls roll.

A photon checks into a hotel. The front desk asks “Do you need help with your luggage?”
The photon replies, “I don’t have any. I’m travelling light.”

A bar walks into a man… oops, wrong frame of reference.

A neutrino walks through a bar.

Old physicists don’t die; their wavefunctions go to zero as time goes to infinity.

Q: What did the Nuclear Physicist have for lunch?
A: Fission Chips.

Q. What did one electron say to the other electron?
A. Don’t get excited. You’ll only get into a state!

Q: Why should you go drinking with neutrons?
A: Wherever they go, there’s no charge.

Q: Where does bad light end up?
A: In prism.

Q: What do physicists enjoy doing the most at sporting events?
A: The Wave

Q: How many theoretical physicists does it take to change a light bulb?
A: Two. One to hold the bulb and one to rotate the universe.

Q: What is blue and smells like red paint?
A: Red paint moving very fast towards you.

Q: What do you get when you cross a chicken with a turkey?
A: |chicken|×|turkey|sinθ.

Q: What does E = mc2 mean?
A: Energy = milk chocolate squared

If sound cannot travel in a vacuum, why are vacuums so noisy?

Schrodinger and Heisenberg were out driving together when they were pulled over by a policeman.
The cop walks up to the window and asks, “Sir, do you know how fast you were going?”
Heisenberg replies, “No, but I know exactly where I was.”
The cop is unamused and orders the physicists to open their trunk. He looks in and sees a dead cat.
Schrodinger replies, “Well, I do now!”

Definition of a tachyon: A gluon that hasn’t dried completely.
Alternate definition: A subatomic particle devoid of taste.

Two atoms were walking down the street. One turns to the other and says,
“Oh, no! I think I lost an electron!”
The other responds, “Are you sure?!?”
“Yes, I’m positive!”

Studying radioactivity is as easy as alpha, beta and gamma.

Einstein, Newton and Pascal were playing Hide and Seek. Einstein slowly counted to 100 while Pascal ran off and hid. Newton drew a square on the floor with a side of one meter and then sat down in the center of the square.
Einstein finished counting, opened his eyes and immediately spotted Newton. “That was easy, I found you Newton!”
Newton replied “No you didn’t, I’m Pascal.”
*Hint* 1 pascal = 1 newton per square meter

Q: Two cats slide off a roof. Which one hit the ground first?
A” The one with smaller “mu”.
*Hint* “mu” or μ is the coefficient of friction

Q: What did the male magnet say to the female magnet?
A: From your backside, I thought you were repulsive. However, after seeing you from the front, I find you rather attractive.

Q: What did one quantum physicist say when he wanted to fight another quantum physicist?
A: Let me atom.

Q: Have you heard of the physicist who got chilled to absolute zero.
A: He’s 0K now.

Q: What’s the difference between an auto mechanic and a quantum mechanic?
A: The quantum mechanic can get the car inside the garage without opening the door.

Q: What did the subatomic duck say?
A: Quark!

A physics grad student meets with his theoretical physics instructor and shows him a graph from his latest experiment.

The instructor points at a peak on the graph and says “You would expect this peak right here. Here is the reason…” and proceeds to spend the next half hour droning out a logical explanation. The grad student interrupts the professor and apologizes. “Sorry, but the graph is upside down.”
“Hmmm, well, you’d expect to see a dip in that position. Here is the reason…”

A newlywed husband is discouraged by his wife’s obsession with physics. Afraid of being second fiddle to her profession, he finally confronts her: “Do you love Physics more than me?”
“Of course not, dear – I love you much more!” Happy, although sceptical, he challenges her: “Well, then prove it!”
Pondering a bit, she responds: “Ok… Let epsilon be greater than zero…”

A block of dry ice was sitting on a table and begins to turn into carbon dioxide gas. After a while, the block is gone and a cloud of CO2 is floating around. A nearby oxygen cloud asks, “Hey, I just saw you go through a phase change…how was it?”
The CO2 cloud replies, “It was sublime!”

A mathematician and a physicist agree to a psychological experiment. The mathematician is put in a chair in a large empty room and a beautiful naked woman is placed on a bed at the other end of the room. The psychologist explains, “You are to remain in your chair. Every five minutes, I will move your chair to a position halfway between its current location and the woman on the bed.” The mathematician looks at the psychologist in disgust. “What? I’m not going to go through this. You know I’ll never reach the bed!” And he gets up and storms out. The psychologist makes a note on his clipboard and ushers the physicist in. He explains the situation, and the physicist’s eyes light up and he starts drooling. The psychologist is a bit confused. “Don’t you realize that you’ll never reach her?” The physicist smiles and replied, “Of course! But I’ll get close enough for all practical purposes!”

Wife walks in on husband, a string theorist, in bed with another woman. He shouts, “I can explain everything!”

Black holes and beautiful women have two things in common.
1. They have very attractive bodies.
2. They are very elusive to the eyes of physicists.

Physics Limerick
There was an old lady called Wright
Who could travel much faster than light.
She departed one day
In a relative way
And returned on the previous night.

# Math Jokes

Mathematics is a rigorous discipline with defined terms and rules. Too bad the same is not true of mathematicians. Here are a few of my favorite math jokes and puns. Post your favorite in the comments section.

Q. Why was 6 afraid of 7?
A. Because 7 8 9!

A math professor is one who talks in someone else’s sleep.

Mathematics is made of 50% formulas, 50% proofs, and 50% imagination.

Old mathematicians never die; they just lose some of their functions.

Mathematics is like love: a simple idea, but it can get complicated.

Life is complex: it has both real and imaginary components.

Math and alcohol don’t mix. Please don’t drink and derive.

The highest moments in the life of a mathematician are the first few moments after one has proved the result, but before they find the mistake.

Q: Why didn’t the Romans find algebra very challenging?
A: Because X was always 10.

Q: Why did the obtuse angle go to the beach?
A: Because it was over 90 degrees

Q: Why was the mathematician sad?
A: He had so many problems.

The integral of d(cabin) over cabin is natural log cabin.

Alternate punchline: Houseboat, you forgot the C.

Q: What do you call an angle that is adorable?
A: acute angle

Q: What do you call a dead parrot?
A: Polygon

Q: What would you call a destroyed angle?
A: A Rectangle

Q: Why was the math student upset when his teacher called him ‘average’?
A: It was a mean thing to say.

Q: Have you heard the latest statistics joke?
A: Probably.

Q: How do mathematicians nag their children?
A: “If I’ve told you n times, I’ve told you n+1 times!”

Q: Why did the chicken cross the Moebius strip?
A: To get to the other … er, um …

Q: What is the simplest way to solve any equation?
A: Multiply both sides by zero.

Q: What is the definition of a polar bear?
A: A rectangular bear after a coordinate transformation.

There are 10 kinds of people in the world, those who understand binary math, and those who don’t.

There are three kinds of people in the world; those who can count and those who can’t.

Three statisticians go out hunting together and spot a deer. The first statistician takes aim and the bullet passes over the animal. The second aims and the shot passes under the deer. The third shouts “We got him!”

I’m so bad at math, the solution to 2n + 2n is 4n to me.

Never argue with a 90º angle, it’s always right.

Q: What do you get when you cross a mosquito with a rock climber?
A: Nothing, you can’t cross a vector with a scalar.

Q: What does the little mermaid wear?
A: An Algebra

A mathematician, a physicist, and an engineer were traveling through Scotland when they saw a black sheep through the window of the train.
“Aha,” says the engineer, “I see that Scottish sheep are black.”
“Hmm,” says the physicist, “You mean that some Scottish sheep are black.”
“No,” says the mathematician, “All we know is that there is at least one sheep in Scotland, and that at least one side of that one sheep is black!”

An engineer, a physicist and a mathematician are staying in a hotel.
The engineer wakes up and smells smoke. He goes out into the hallway and sees a fire, so he fills a trash can from his room with water and douses the fire. He goes back to bed.
Later, the physicist wakes up and smells smoke. He opens his door and sees a fire in the hallway. He walks down the hall to a fire hose and after calculating the flame velocity, distance, water pressure, trajectory, etc. extinguishes the fire with the minimum amount of water and energy needed.
Later, the mathematician wakes up and smells smoke. He goes to the hall, sees the fire and then the fire hose. He thinks for a moment and then exclaims, “Ah, a solution exists!” and then goes back to bed.

One day a farmer called up an engineer, a physicist, and a mathematician and asked them to fence of the largest possible area with the least amount of fence.
The engineer made the fence in a circle and proclaimed that he had the most efficient design.
The physicist made a long, straight line and proclaimed “We can assume the length is infinite…” and pointed out that fencing off half of the Earth was certainly a more efficient way to do it.
The Mathematician just laughed at them. He built a tiny fence around himself and said “I declare myself to be on the outside.”

A newlywed husband is discouraged by his wife’s obsession with mathematics. Afraid of being second fiddle to her profession, he finally confronts her: “Do you love math more than me?”
“Of course not, dear – I love you much more!”
Happy, although sceptical, he challenges her: “Well, then prove it!”
Pondering a bit, she responds: “Ok… Let epsilon be greater than zero…”

Several scientists were all posed the following question: “What is π?”
The engineer said: “It is approximately 3 and 1/7.”
The physicist said: “It is 3.14159.”
The mathematician thought a bit, and replied “It is equal to π”.

In Alaska, where it gets very cold, π is only 3.00. As you know, everything shrinks in the cold. They call it Eskimo π.

Math and Lightbulbs

Q: How many mathematicians does it take to change a lightbulb?
A1: None, it is left to the student as an exercise.
A2: None. A mathematician can’t change a lightbulb, but can prove a solution exists.
A3: The answer is intuitively obvious.
A4: If k mathematicians can change a light bulb, and if one more simply watches them do it, then k+1 mathematicians will have changed the light bulb. Therefore, by induction, for all n in the positive integers, n mathematicians can change a light bulb.
A5: Four: One to do the work, three to co-author the paper.