Find square of number between 80 to 100 in just 5 seconds without calculator

Find 3 rational numbers between 4 and 5

Find the squares of the number127

Find the sum of all odd numbers between 100 and 200.

Find the sum of all odd numbers between 100 and 200.

Find three rational numbers between -2 and 5.

Find three rational Number between -1/5 and -2/5 .

Find four rational numbers between 3/5 and 4/5.

Find numbers between 1 and 100 having exactly three factors.

Find five rational numbers between 3/5 and 4/5 .

Find the number of digits in the square root of each of the following numbers (without any calculation). (i) 64 (ii) 144 (iii) 4489 (iv) 27225 (v) 390625