### 2-digit Square

A 2-Digit number is squared. When this 2-digit number is reversed and squared, the difference between the squares is also a square. What is the 2-digit number?

### Consecutive Squares

The squares of any 8 consecutive numbers can be arranged into two sets of four numbers with the same sum. True of false?

### Plus Minus

Can you explain the surprising results Jo found when she calculated the difference between square numbers?

# Clever Calculation

##### Age 14 to 16 ShortChallenge Level

Without using a calculator, or performing any long multiplication calculations, find the value of
$$2017^2-2015\times2019$$

This problem is taken from the World Mathematics Championships
You can find more short problems, arranged by curriculum topic, in our short problems collection.