Mental calculations

There are 106 NRICH Mathematical resources connected to Mental calculations

problem

Favourite

Ladybirds in the garden

Age

5 to 7

Challenge level

In Sam and Jill's garden there are two sorts of ladybirds with 7 spots or 4 spots. What numbers of total spots can you make?

problem

Favourite

Find the difference

Age

5 to 7

Challenge level

Place the numbers 1 to 6 in the circles so that each number is the difference between the two numbers just below it.

problem

Favourite

Where can we visit?

Age

11 to 14

Challenge level

Charlie and Abi put a counter on 42. They wondered if they could visit all the other numbers on their 1-100 board, moving the counter using just these two operations: x2 and -5. What do you think?

problem

Favourite

The brown family

Age

5 to 7

Challenge level

Use the information about Sally and her brother to find out how many children there are in the Brown family.

problem

Favourite

A square of numbers

Age

7 to 11

Challenge level

Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?

problem

Favourite

Power countdown

Age

14 to 16

Challenge level

In this twist on the well-known Countdown numbers game, use your knowledge of Powers and Roots to make a target.

problem

Favourite

Roll these dice

Age

7 to 11

Challenge level

Roll two red dice and a green dice. Add the two numbers on the red dice and take away the number on the green. What are all the different possible answers?

problem

Favourite

Highest and lowest

Age

7 to 11

Challenge level

Put operations signs between the numbers 3 4 5 6 to make the highest possible number and lowest possible number.

problem

Favourite

Think of a number, add one, double it, take away 3, add the number you first thought of, add 7, divide by 3 and take away the number you first thought of. You should now be left with 2. How do I know?

problem

Favourite

Strike it out

Age

5 to 11

Challenge level

Use your addition and subtraction skills, combined with some strategic thinking, to beat your partner at this game.

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Mental calculations

Ladybirds in the garden

Find the difference

Where can we visit?

The brown family

A square of numbers

Power countdown

Roll these dice

Highest and lowest

Mind reading

Strike it out