The trick of number 5

If we need to find the square of any number ending in 5,
write 25 as the last 2 digits, then multiply the digit of the number (other than 5) with the next consecutive digit, write this answer as the first digit.

For example :
65 x 65
Step 1 : write 25 as the last 2 digits ___ 25
Step 2 : Multiply the first digit by the next consecutive digit.
Here the digit of the number other than 5 is 6, the next consecutive digit is 7,
6 x 7 = 42,
Hence 65 x 65 = 4225

Let's try the same trick with a bigger number
435 x 435
Step 1 : write 25 as the last 2 digits ___ 25
Step 2 : Multiply the digit (other than 5) by the next consecutive digit.
Here the digits of the number (other than 5 ) are 43, the next consecutive number to 43 is 44, 43 x 44 = 1892,

Hence 435 x 435 = 189225

Isn't that interesting!


From
10on10 Team