Challenge Level

Choose any four digits (from 0, 1, 2, ... , 9) and place them in the cells below (you can repeat digits).

Read the two 2-digit numbers across and add them together.

Read the two 2-digit numbers down and add them too.

Then add these two totals together.

Try a few examples of your own.

How many ways are there of doing this?

If we use four 0s, the total would be 0.

If we use four 9s, the total would be 396.