At the top left there are four numbers in a small square.
On the right you write the sum of the two numbers for each row.
At the bottom you write the sum for each column.
In the bottom right corner is the total of all four numbers.
Tip: the two row sums add up to the total.
The same goes for the two column sums.
The green numbers show the solution.
Example
- 20, 40, 32, 28, 60
- 20, 10, 18, 12, 30
- 30, 10, 25, 15, 40