### 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?

### What's Possible?

Many numbers can be expressed as the difference of two perfect squares. What do you notice about the numbers you CANNOT make?

### Why 24?

Take any prime number greater than 3 , square it and subtract one. Working on the building blocks will help you to explain what is special about your results.

# Plus Minus

##### Stage: 4 Challenge Level:
Look at the diagram below:
Which part of the diagram represents $85^2$?
Which part represents $65^2$?
Which part represents $85^2-65^2$?