There are 52 NRICH Mathematical resources connected to Mental calculations, you may find related items under Calculations and numerical methods.
Broad Topics > Calculations and numerical methods > Mental calculations
Can you use the clues to complete these 5 by 5 Mathematical Sudokus?
Can you use the clues to complete these 4 by 4 Mathematical Sudokus?
Can you spot the mistake in this video? How would you work out the answer to this calculation?
Can you put these four calculations into order of difficulty? How did you decide?
Can you match these calculation methods to their visual representations?
Which two items of fruit could Kate and Sam choose? Can you order the prices from lowest to highest?
Order these four calculations from easiest to hardest. How did you decide?
How many ways can you find to put in operation signs (+, −, ×, ÷) to make 100?
Can you find ways to put numbers in the overlaps so the rings have equal totals?
What is the smallest number of answers you need to reveal in order to work out the missing headers?
This group activity will encourage you to share calculation strategies and to think about which strategy might be the most efficient.
Mathematicians are always looking for efficient methods for solving problems. How efficient can you be?
Who said that adding, subtracting, multiplying and dividing couldn't be fun?
Here is a chance to play a version of the classic Countdown Game.
In this twist on the well-known Countdown numbers game, use your knowledge of Powers and Roots to make a target.
Use the differences to find the solution to this Sudoku.
The puzzle can be solved with the help of small clue-numbers which are either placed on the border lines between selected pairs of neighbouring squares of the grid or placed after slash marks on the intersections between two diagonally adjacent squares.
Can you arrange these numbers into 7 subsets, each of three numbers, so that when the numbers in each are added together, they make seven consecutive numbers?
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?
Practise your tables skills and try to beat your previous best score in this interactive game.
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?
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?
Investigate how you can work out what day of the week your birthday will be on next year, and the year after...
In this article for primary teachers, Ems outlines how we can encourage learners to be flexible in their approach to calculation, and why this is crucial.
Number problems for inquiring primary learners.
Dicey Operations for an adult and child. Can you get close to 1000 than your partner?
Related resources supporting pupils' understanding of multiplication and division through playing with numbers.
Resources to support understanding of multiplication and division through playing with number.
Some additional activities to develop children's understanding of addition and subtraction of number through playing with number.
More resources to support understanding multiplication and division through playing with numbers
Complete the Mathdoku grid using the clues. Can you convince us that the number you have chosen for each square has to be correct?
What would you do if your teacher asked you add all the numbers from 1 to 100? Find out how Carl Gauss responded when he was asked to do just that.
George and Jim want to buy a chocolate bar. George needs 2p more and Jim need 50p more to buy it. How much is the chocolate bar?
These grids are filled according to some rules - can you complete them?
This is a game for two players. What must you subtract to remove the rolled digit from your number? The first to zero wins!
A game for 2 or more players with a pack of cards. Practise your skills of addition, subtraction, multiplication and division to hit the target score.
A game for 2 players. Practises subtraction or other maths operations knowledge.
Practise your number bonds whilst improving your memory in this matching pairs game.
A game for 2 players. Using 2 dice, some counters and a games board, can you form a line of counters from one side of the board to the other?
A game for 2 or more players. Practise your addition and subtraction with the aid of a game board and some dried peas!
A game for 2 or more people. Starting with 100, subratct a number from 1 to 9 from the total. You score for making an odd number, a number ending in 0 or a multiple of 6.
Can you spot the similarities between this game and other games you know? The aim is to choose 3 numbers that total 15.
An ordinary set of dominoes can be laid out as a 7 by 4 magic rectangle in which all the spots in all the columns add to 24, while those in the rows add to 42. Try it! Now try the magic square...
Here are three 'tricks' to amaze your friends. But the really clever trick is explaining to them why these 'tricks' are maths not magic. Like all good magicians, you should practice by trying them. Can you explain how they work?
Place the numbers 1, 2, 3,..., 9 one on each square of a 3 by 3 grid so that all the rows and columns add up to a prime number. How many different solutions can you find?