On dividing each of 12 and 23 by a number greater than 1, we get the same remainder. What is the remainder?

The sum of the digits of a two-digit number added to the product of the digits, give the original number again. What is the digit in the one's place of the number?

The picture shows a stick just fitting into a rectangular box with dimensions 2 cm, 3 cm and 6 cm (the stick runs along the space diagonal of the box). What is the length of the stick?

A two-digit number divided by another two-digit number gives 6.25. What do we get if we multiply these two numbers?

When the length of each side of a square was reduced by 20%, its area became 16 square centimeters. What was the area of the original square?