Skip to main content
### Number and algebra

### Geometry and measure

### Probability and statistics

### Working mathematically

### For younger learners

### Advanced mathematics

# Staircase Sum

The digits 1, 2, 3, 4, 5, 6, 7, 8 and 9 are to be written in the squares so that every row and every column of three squares has a total of 13. Two numbers have already been entered. What is the value of n?

If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.

Or search by topic

Age 11 to 14

ShortChallenge Level

- Problem
- Solutions

The digits 1, 2, 3, 4, 5, 6, 7, 8 and 9 are to be written in the squares so that every row and every column of three squares has a total of 13. Two numbers have already been entered. What is the value of n?

If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.

This problem is taken from the UKMT Mathematical Challenges.

You can find more short problems, arranged by curriculum topic, in our short problems collection.