Question

Using arithmetic identity find the square of 87.

Answer 1

We can find the square of 87 by using arithmetic identity:
We know that $(a+b{)}^2=a^2+b^2+2ab$
Using this,$(87{)}^2=(80{)}^2+(7{)}^2+2\times (80)\times (7)$
$(87{)}^2=6400+49+1120$
Hence, $(87{)}^2=7569$