Question

how to find the square of 402 by observation method​

Answer 1

Answer:

Hope that i will help you

Step-by-step explanation:

If the given number is below 100 like 98 so we will use the formula (x-y)square= x square- 2xy + y square

If the given number is above 100 like 108 so we will use the formula ( x+y) square= x square+ 2xy+ y square

Here, the number is above 100 so we will use the formula (x+y)=x square+ 2xy + y square

we will take 400 as x and 2 as y

=(400+2)square= 400square+(2×400×2)+2 square

(402)square= the square of 400 i.e. 160000+(2×400×2)+2square

=160000+(800×2)+ the square of 2 is 4

=160000+1600+4

=161600+4

=161604 is the answer