A calculation square has nine numbers in three rows and three columns.
The sums are shown at the edge, so what each row and each column add up to.
Some fields are empty. You have to find the missing numbers.
Example:
First row: 5 + 8 + ? gives 16. The 3 is missing, because 5 + 8 + 3 = 16.
First column: 5 + 6 + ? gives 16. The 5 is missing, because 5 + 6 + 5 = 16.
Always keep calculating where only one number is still missing.
The numbers filled in show the solution.
Example
- 3,7,5
For parents
What does this exercise practice?
Determine missing addends using row and column sums and practise grouping numbers.
Common pitfalls
Children sometimes add up all three fields even though one is still empty. Tip: first find the row where only one number is missing, then work it out.
How to practice at home
Lay out three rows with building blocks, count each row and each column. Cover one stack and let your child guess the missing number.
Related: Number square, Number cross, Table