Here is a super cool square trick your school didn’t teach you or you probably didn’t know about!! How to do the square of 2-digit no. in your mind so you should never use a calculator for that.

Squaring of a 2-digit no. in your mind!!

As you probably know, the square of a number is a number
multiplied by itself. For example, the square of 7 is 7 * 7 = 49. So here’s the trick for so-called “How to do the square of 2-digit no. in your mind“.That method is especially simple when the number ends in 5, so let’s do that trick now. To square a two-digit number that ends in 5, you need to
remember only two things:

  1. The answer begins by multiplying the first digit by the next higher
    digit.
  2. The answer ends in 25

For example, to square the number 65, we simply multiply the first digit (6) by the next-higher digit (7), then attach 25. Since 6*7=42, the answer is 4225. Therefore, 65 * 65 = 4225. How about the square of 85? Since 8 * 9 = 72, we immediately get 85 * 85 = 7225.

Cool and easy……..isn’t it!!!

We can use a similar trick when multiplying two-digit numbers with the same first digit, and second digits that sum to 10. The answer begins the same way that it did before (the first digit multiplied by the next higher digit), followed by the product of the second digits. For example, let’s try 83 * 87. (Both numbers begin with 8, and the last digits sum to 3 + 7 = 10.) Since 8 * 9 = 72, and 3 * 7 = 21, the answer is 7221.

Similarly, 84 * 86 = 7224.
Now it’s your turn.

26 * 24 = ?

How does the answer begin? With 2 * 3 = 6. How does it
end? With 6 * 4 = 24. Thus 26 * 24=624. Remember that to use this method, the first digits have to be the same, and the last digits must sum to 10. Thus, we can use this method to instantly determine that

31 * 39 = 1209
32 * 38 = 1216
33 * 37 = 1221
34 * 36 = 1224
35 * 35 = 1225

Isn’t it easy and cool..!!!

Reference: Secrets of Mental Math: The Mathemagician’s Guide to Lightning Calculation and Amazing Math Tricks