### Number Detective

Follow the clues to find the mystery number.

### Make 37

Four bags contain a large number of 1s, 3s, 5s and 7s. Pick any ten numbers from the bags above so that their total is 37.

### Red Even

You have 4 red and 5 blue counters. How many ways can they be placed on a 3 by 3 grid so that all the rows columns and diagonals have an even number of red counters?

# Becky's Number Plumber

##### Age 7 to 11 Challenge Level:

This problem has been inspired by learners who were working on the Become Maths Detectives Project.

You may like to watch the video in the Become Maths Detective Project before having a go at this activity.

Becky created a number plumber which multiplies by $5$ and subtracts $4$.
Click on the picture to explore Becky's number plumber.

What do you notice about the units digit of the answer each time?
Can you explain why this happens?
Can you find any other numbers that work in a similar way?