Question

1515 this number become a perfect square then which number is add

Answer 1

The difference between that number and 1515 is the number you have to add to 1515 to make it a perfect square.

The easiest way to find the required perfect square is to first find a round number whose perfect square is close to 1515.

Here, 40^2 = 1600 is the closest.

Now try to find if there is a perfect square between 1515 and 1600.

So, we go one number down from 40 i.e. we check for square of 39.

There is an easy way to find out 39^2 if you do not know the answer.

39^2 = 40^2 - (39+40)

This is based on the fact that (a - 1)^2 = a^2 - 2a + 1 = a^2 - a - a + 1 = a^2 - (a + a - 1)

= a^2 - ( a + (a - 1))

Thus, 39^2 = 1600 - 79 = 1521

1521 = 1515 + 6.

Hence, 6 is the smallest number to be added to 1515 to make it a perfect square.

hope it helps...

Answer 2

we have to add 6 in 1515 to make complete square of 39