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### Number and algebra

### Geometry and measure

### Probability and statistics

### Working mathematically

### Advanced mathematics

### For younger learners

# Satisfying Statements

If you are not sure what a triangular number is, take a look at Picturing Triangular Numbers

You might find it useful to record each person's numbers on a 1 to 100 grid.

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### Adding All Nine

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Age 11 to 14

Challenge Level

- Problem
- Getting Started
- Student Solutions
- Teachers' Resources

If you are not sure what a triangular number is, take a look at Picturing Triangular Numbers

You might find it useful to record each person's numbers on a 1 to 100 grid.

Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some other possibilities for yourself!