Find the square of $31$ without actual multiplication.

Find the square of $42$ without actual multiplication.

Find the squares of$86$without actual multiplication.

Find the squares of$94$ without actual multiplication.

Find the square of the following number containing $5$ in unit's place:

$45$

Find the square of the following number containing $5$ in unit's place:

$305$

Find the square of the following number containing $5$ in unit's place:

$525$

Write a Pythagorean triplet whose one number is

$8$

Write a Pythagorean triplet whose one number is $15$.