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There are 89 NRICH Mathematical resources connected to Mental calculations, you may find related items under Calculations and numerical methods.
Broad Topics > Calculations and numerical methods > Mental calculationsCan you work out some different ways to balance this equation?
Can you complete this calculation by filling in the missing numbers? In how many different ways can you do it?
In this game for two players, the idea is to take it in turns to choose 1, 3, 5 or 7. The winner is the first to make the total 37.
Here are some short problems for you to try. Talk to your friends about how you work them out.
This problem is designed to help children to learn, and to use, the two and three times tables.
Can you use the information to find out which cards I have used?
What is the smallest number of answers you need to reveal in order to work out the missing headers?
Tom and Ben visited Numberland. Use the maps to work out the number of points each of their routes scores.
If you have ten counters numbered 1 to 10, how many can you put into pairs that add to 10? Which ones do you have to leave out? Why?
What happens when you add the digits of a number then multiply the result by 2 and you keep doing this? You could try for different numbers and different rules.
This group activity will encourage you to share calculation strategies and to think about which strategy might be the most efficient.
Can you each work out the number on your card? What do you notice? How could you sort the cards?
Use your addition and subtraction skills, combined with some strategic thinking, to beat your partner at this game.
Here is a chance to play a version of the classic Countdown Game.
Place the numbers 1 to 6 in the circles so that each number is the difference between the two numbers just below it.
These eleven shapes each stand for a different number. Can you use the number sentences to work out what they are?
A resource to try once children are familiar with number lines, and they have begun to use them for addition. It could be a good way to talk about subtraction. Leah and Tom each have a number line. Can you work out where their counters will land?
Try grouping the dominoes in the ways described. Are there any left over each time? Can you explain why?
Can you hang weights in the right place to make the the number balance balanced?
Do you agree with Badger's statements? Is Badger's reasoning 'watertight'? Why or why not?
These sixteen children are standing in four lines of four, one behind the other. They are each holding a card with a number on it. Can you work out the missing numbers?
Tim had nine cards each with a different number from 1 to 9 on it. How could he have put them into three piles so that the total in each pile was 15?
As you come down the ladders of the Tall Tower you collect useful spells. Which way should you go to collect the most spells?
Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?
Use the information about Sally and her brother to find out how many children there are in the Brown family.
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?
A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.
Practise your tables skills and try to beat your previous best score in this interactive game.
Ten cards are put into five envelopes so that there are two cards in each envelope. The sum of the numbers inside it is written on each envelope. What numbers could be inside the envelopes?
The value of the circle changes in each of the following problems. Can you discover its value in each problem?
Sally and Ben were drawing shapes in chalk on the school playground. Can you work out what shapes each of them drew using the clues?
Katie had a pack of 20 cards numbered from 1 to 20. She arranged the cards into 6 unequal piles where each pile added to the same total. What was the total and how could this be done?
Find at least one way to put in some operation signs to make these digits come to 100.
What do you notice about these squares of numbers? What is the same? What is different?
Put operations signs between the numbers 3 4 5 6 to make the highest possible number and lowest possible number.
Can you find two butterflies to go on each flower so that the numbers on each pair of butterflies adds to the number on their flower?
Make one big triangle so the numbers that touch on the small triangles add to 10.
Arrange the numbers 1 to 6 in each set of circles below. The sum of each side of the triangle should equal the number in its centre.
Lolla bought a balloon at the circus. She gave the clown six coins to pay for it. What could Lolla have paid for the balloon?
Use these four dominoes to make a square that has the same number of dots on each side.
Using the cards 2, 4, 6, 8, +, - and =, what number statements can you make?
Find all the numbers that can be made by adding the dots on two dice.
Use the 'double-3 down' dominoes to make a square so that each side has eight dots.
Noah saw 12 legs walk by into the Ark. How many creatures did he see?
Can you go through this maze so that the numbers you pass add to exactly 100?
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?