Addition and subtraction

There are 355 NRICH Mathematical resources connected to Addition and subtraction
This Pied Piper of Hamelin
problem
Favourite

This pied piper of hamelin

Age
7 to 11
Challenge level
filled star filled star empty star

Investigate the different numbers of people and rats there could have been if you know how many legs there are altogether!

Prison Cells
problem
Favourite

Prison cells

Age
7 to 11
Challenge level
filled star filled star empty star
There are 78 prisoners in a square cell block of twelve cells. The clever prison warder arranged them so there were 25 along each wall of the prison block. How did he do it?
A Square of Numbers
problem
Favourite

A square of numbers

Age
7 to 11
Challenge level
filled star empty star empty star
Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?
Caterpillars
problem
Favourite

Caterpillars

Age
5 to 7
Challenge level
filled star filled star empty star
These caterpillars have 16 parts. What different shapes do they make if each part lies in the small squares of a 4 by 4 square?
Find the Difference
problem
Favourite

Find the difference

Age
5 to 7
Challenge level
filled star filled star empty star
Place the numbers 1 to 6 in the circles so that each number is the difference between the two numbers just below it.
Sort them out (1)
problem
Favourite

Sort them out (1)

Age
5 to 7
Challenge level
filled star empty star empty star
Can you each work out the number on your card? What do you notice? How could you sort the cards?
Can you Make 100?
problem
Favourite

Can you make 100?

Age
11 to 14
Challenge level
filled star empty star empty star
How many ways can you find to put in operation signs (+, −, ×, ÷) to make 100?
Consecutive Numbers
problem
Favourite

Consecutive numbers

Age
7 to 14
Challenge level
filled star empty star empty star

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

2, 4, 6, 8
problem
Favourite

2, 4, 6, 8

Age
5 to 7
Challenge level
filled star filled star filled star
Using the cards 2, 4, 6, 8, +, - and =, what number statements can you make?
Neighbours
problem
Favourite

Neighbours

Age
7 to 11
Challenge level
filled star filled star empty star
In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?