Reach 100

Reach 100 printable sheet

Here is a grid of four boxes:

You must choose four different digits from 1 - 9 and put one in each box. For example:

This gives four two-digit numbers:

52 (reading along the first row)

19 (reading along the first row)

51 (reading down the left-hand column)

29 (reading down the right-hand column)

In this case their sum is 151.

Try a few examples of your own.
Is there a quick way to tell if the total is going to be even or odd?


Your challenge is to find four different digits that give four two-digit numbers which add to a total of 100.

How many ways can you find of doing it?
 

You may be interested in the other problems in our Mastering Mathematics: Developing Generalising and Proof Feature.

This problem is adapted from Make 200 from 'Mathematical Challenges for Able Pupils Key Stages 1 and 2', published by DfES.