7 Math Tricks That Will Blow Your Mind

Many people find math to be difficult, and big sums can look overwhelming at first glance. Whether you’re preparing for the SATs and need to pick up some math skills quickly, or whether you’re brushing up to take an advanced course in college, learning a few helpful math tricks can help you feel more confident without a calculator.

Take a look at these simple math tricks, and try them out yourself. We’ve also included a few cool math tricks just to impress your friends and learn to have a little fun with numbers.

Adding Large Sums

Adding up large numbers in your head can be overwhelming. Here is a quick trick to help make larger sums simpler. 

The first step is to round up big numbers to the closest ten. For example, if you’re adding 644 + 238, you’ll round up to 650 and 240. Automatically this has already simplified your work. 

Now you need to add up 600 and 200. 6 + 2 is 8, so you have 800.

Next, you’ll add up 50 and 40. 5 + 4 is 9, so you have 90. 

Altogether you now have 890 as you answer.

This is the rounded up answer. If you need the exact sum, then you’ll simply add or subtract the missing numbers from when you rounded up the first sums. 

650 is 6 more than 644, and 240 is 2 more than 238. 

Together you have 8 (6 + 2), and this is the number that you’ll subtract from 890.

890 – 8 = 882.

Altogether: 644 + 238 = 882.

It may seem complicated at first, but once you do it in your head a few times it will be a treasured trick for doing big sums without a calculator.

Subtracting from 1,000

This is a cool trick for subtracting a big sum from 1,000. 

Let’s use the example 1,000 – 546. 

First we subtract the first two numbers from 9:

9 – 5 = 4

9 – 4 = 5

Then, we subtract the final number from 10:

10 – 6 = 4

Put these numbers together and you have the answer.

The answer is 1,000 – 546 = 454

Multiplying by 5

Here’s a quick way to multiply 5 by both even and odd numbers.

Even Numbers

In order to multiply 5 by an even number, you’ll simply cut the number in half and add a 0.

Let’s use the example 5 x 4.

Cut 4 in half to make 2, and then add a 0 to it to make 20.

5 x 4 = 20

Odd Numbers

Now, multiplying 5 by odd numbers has a different trick.

Here, you’ll want to subtract 1 from the number, cut that number in half, and add a 5 for the answer.

For example, 5 x 45.

Subtract 1 from 45 to get 44. 

Then cut 44 in half to get 22. 

Add a 5 after 22, and there’s your answer: 225.

5 x 45 = 225

Multiplication with Fingers

Many people still use their fingers to do simple addition and subtraction. Did you know that you can also use your finger for multiplying by 9?

Here’s what you do: 

Place your hands up in front of you with your palms facing away from you. 

Next, count your fingers from left to right, and fold down the number finger that you are multiplying by nine. So, if you are trying to figure out 9 x 3, you will fold down your 3rd finger, which is the middle finger on your left hand.

Next, count how many fingers remain before your folded finger. The answer here will be 2. 

Then count the fingers remaining after your folded finger, which will be 7 in this case. 

Your final answer will be the two numbers together: 27.

9 x 3 = 27

Multiplying by 9

Many people find multiplication by 9 a little confusing. Here’s a quick trick to make it easy. Note that this trick only works for the basic multiplication table from 1 – 10.

Let’s use the example of 9 x 3. 

First, subtract 1 from the number that you are multiplying by 9. So, in our example, 3 minus 1 will be 2. This number will be the first digit of your answer.

Next, subtract that same number from 9, and that will be the second digit of your answer. So, 9 minus 2 is 7.

Put the two numbers together and you get 27.

9 x 3 = 27

Percentage Trick

Do you need to quickly figure out a percentage of a large sum? Say you need to figure out 5% of $235.00. Simple, here’s an easy trick.

First move the decimal in 235 one spot to the left (if it’s not written out in this form, assume that the decimal appears after the sum). 

So, 235 becomes 23.5.

Next, divide the number by half. So, 23.5 becomes 11.75.

Now you have your answer. 11.75 is 5% of 235.

4 More Math Tricks to Impress Your Friends

The answer is 2

Here’s a cool math trick to use on your friends:

Step 1: Think of a number.

Step 2: Now, multiply that number by 3.

Step 3: Add 6 to that.

Step 4: Divide your number by 3

Step 5: Subtract your original number from the number in step 4.

Your answer is 2.

The answer is 37

Here’s a similar trick that works every time:

Step 1: Think of a three digit number where all the numbers are the same. For example, 333 or 444, etc.

Step 2: Add up the numbers. 

So, 3 + 3 + 3 = 9.

Step 3: Divide your original number by your answer from step 2.

333 divided by 9 is…37.

The answer will always be 37. Try it out yourself to see!

The answer contains 1, 2, 4, 5, 7, and 8

This one may require a calculator but here’s another trick, just for fun:

Step 1: Think of a number from 1 to 6.

Step 2: Multiply your number by 9.

Step 3: Multiply that number by 111 

(here’s where you may want to use a calculator, unless you want to go back and use the large sums trick from earlier in the article!)

Step 4: Now, multiply your number by 1,001

Step 5: Finally, divide your answer by 7.

Your answer should contain the numbers 1, 2, 4, 5, 7, and 8.

For example, if your original number was 6, your answer will be 714,285.

Memorize Pi

This trick is cute for anyone who appreciates word play:

If you’d like to remember the first digits of pi, just count the number of letters in each word of the following sentence:

“How I wish I could calculate pi.”

3.141592

Wrapping Up

Math can be difficult for many people, especially when you need to deal with larger sums, but a few simple math tricks can go a long way and help you feel more comfortable with numbers. 

Whether you’re attending school and need to take a math test, or whether you need some tips for those times when you don’t want to pull out a calculator, these math tricks will help you feel more confident.