### Cuisenaire Rods

These squares have been made from Cuisenaire rods. Can you describe the pattern? What would the next square look like?

### Making Boxes

Cut differently-sized square corners from a square piece of paper to make boxes without lids. Do they all have the same volume?

### Special 24

Find another number that is one short of a square number and when you double it and add 1, the result is also a square number.

# A Right Charlie

## A Right Charlie

Charlie's house number is a three-digit square number.

This number when reversed is also a square and is Charlie's telephone extension at work.

His car registration number is  a four-digit square number and is formed from his house number by repeating the right hand digit.

What is Charlie's house number?

### Why do this problem?

This problem requires systematic working and will increase children's familiarity with square numbers.

### Key questions

What three-digit square numbers do you know?
How do you know you haven't missed out any three-digit square numbers?

### Possible extension

Some pupils may enjoy the challenge of Gran, How Old Are You? which is a similar numerical problem.

### Possible support

Many children will find the use of a calculator invaluable for this problem.