### Number Detective

Follow the clues to find the mystery number.

### Six Is the Sum

What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?

### ABC

In the multiplication calculation, some of the digits have been replaced by letters and others by asterisks. Can you reconstruct the original multiplication?

# 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?