Math Hacks to Conquer Mental Math In No Time

No math gene? Just a little bit of practice every day will help you solve math problems quickly in your head! Explore the math hacks that will help you do mental math within mere seconds.

Math Hack #1 Simple multiplication by 11

Multiplication by 11 is so easy that you will be able to do mental multiplication within seconds.

Below is the easiest way to multiply two-digit numbers by 11 in just two steps.

35 x 11=?

Solution: Add 3 and 5 to get 8. Put 8 in between 3 and 5 to get 385.

Answer: 35 x 11=385

Ta-da! You’ve solved the problem!

But what if the sum of the two digits happens to be greater than 9? Let’s modify the trick a bit so that it suits our purpose.

79 x 11=?

Solution: Add the two digits: 7+9=16 Put 6 in between 7 and 9 to get 769 Add the 1 from 16 and the 7 from 769 to get 869.

Answer: 79 x 11=869

Pretty easy, isn’t it?

Math Hack #2 Subtraction from 1,000, 10,000, 100,000, etc.

Subtracting from 1,000, 10,000, or even 100,000 is no longer a nightmare with this simple math-hack.

1,000 – 547 =?

Solution: Subtract all but the last digit of the subtrahend from 9: 9-5=4 and 9-4=5 Subtract the last digit from 10: 10-7=3

Answer: 1,000-547=453

Math Hack #3 Fast Addition Technique


Look at a shockingly simple method that will help you add numbers without using a calculator!


Solution: You need to add 2 to 88 to round it to the nearest ten, which in this case is 90. Thus, break 7 into 2 and 5. First, add 2 to 88 to get 90, then complete the addition by adding 5 to 90: 88+2+5=90+5=95

Answer: 88+7=95

When adding two-digit numbers, consider the place value of each digit.


Solution: Break the numbers apart by their place value: 56 is 5 tens and 6 ones and 38 contains 3 tens and 8 ones. Add the digits according to their place value: 50+30=80 (tens) and 6+8=14(ones) Complete the addition: 80+14=94

Answer: 56+38=50+30+6+8=80+14=94

The same technique can also be used for larger numbers, though it will involve more steps to solve a math problem.

Math Hack #4 Easy way to divide by 5

Ready for more? Let’s see how to divide any large number by 5 quickly.


Solution: Multiply 433 by 2 to get 866 Move the decimal point one place to the left to get 86.6.

Answer: 433/5=86.6

Math Hack #5 Square Numbers in your Head

Now let’s find out how a bit of algebra makes squaring two-digit numbers much easier.


Solution: Let’s break 32 into 30 and 2 to make it fit the formula (a+b)2=a2+2ab+b2. Do the calculations: (30+2)2=302+2x30x2+22=900+120+4=1,024.

Answer: 322=1,024

Math Hack #6 Multiply by 4 in seconds


Have a look at a simple multiplication hack based on the expression 2x2=4.

51 x 4=?

Solution: Double 51 to get 102 Add 102 and 102 to get 204

Answer: 51 x 4 =51x2+51x2=102+102=204

Math Hack #7 How to multiply by 9 in your head

Multiplication is no longer one of the most difficult math operations to master. Find out how to multiply by 9 in your head.

55 x 9=?

Solution: Multiply 55 by 10 to get 550. Subtract 55 from 550. The answer is 495.

Answer. 55 x 9=55 x 10 – 55=550-55=495