And the answer is...

This can be used as a whole class mental/oral starter or in the main part of the lesson.

Children will consolidate their understanding of the four operations and the arithmetic laws.
Children will develop calculator skills and use them in checking calculations.

NNS References

Several aspects of the Calculations strand for Years 5 and 6 are consolidated in this activity.

Using a calculator

Checking the results of calculations


A random number generator.
A class set of calculators.
Pencils and paper for jotting down the calculation if it is complex.


Use the random number generator to select a number to be the answer e.g. 42
Write this on the board.
Ask the children to suggest a question that has 42 as the answer. When one child suggests a question the others check.

Extensions and variations

The answer is a decimal number.
The answer is a negative number.
Each question must include a particular operation (e.g. multiplication).
Each question must include a number (e.g. 4).
Each question must include at least two operations.
Each question must include a decimal.

Observations, intervention and questions to ask

Are the children challenging themselves or just giving the simplest question?
Do children use inverse operations to check?
Are children demonstrating an understanding of the arithmetic laws in their calculations?
Are children using calculators appropriately?
How did you check the calculation?
What facts did you use to help you?

What learning has taken place?

Children have consolidated their knowledge and understanding of the four operations.
Children understand the effect of the arithmetic laws.