Every small square has four fields.
On the right and at the bottom it says what each row and each column adds up to.
One field is empty. Find the missing number so that all the sums are right.
Example: at the top left is 3, at the bottom left 6, at the bottom right 2.
The top row should make 8. What is missing at the top right?
3 plus 5 makes 8, so the 5 belongs in the empty field.
Then check: the columns have to give their sums as well.
The numbers filled in show the solution.
Example
For parents
What does this exercise practice?
Complete numbers in a grid so that the row and column sums fit. That practices plus, minus and checked trial and error.
Common pitfalls
Some children look at only one sum. What matters is that the number found fits in both directions, in its row and in its column.
How to practice at home
Build a small two-by-two grid with building blocks and count the rows and columns together.
Related: Number cross, Table, Calculation