This is a game for two players, a group of 3 or 4 players, or for the whole class. You will need to download and cut out or otherwise make 2 sets of these 24 cards.
Separate the 40 number cards from the 8 operation cards and shuffle them separately to […]
Target -10 with (-3) and (-5); Target -60 with (-6) and (+9); Target + 45 with (-5) and […]
We need to use negative numbers for sub zero temperatures and for distances between the highest peaks on earth and the deepest points in the oceans and deep mines.
Mauna Kea’s summit is 4205 metres above sea level but it extends below the sea surface to a depth of -6000 metres. This makes Mauna Kea […]
Is there more than one?
Can you find them all?
Can you provide a convincing argument that you have found them all?
Is it always possible, from any set of five positive whole numbers, to choose three numbers that add up to a multiple of 3?
For example, if you start with 4, 7, 11, 12 and 18, you can choose 4, 11 and 12 which add up to 27 (a multiple of 3).
The letters A, B, C, D, E, F, G and H correspond to the numbers from 0 to 7 with no repetitions.
Use the clues that A+C=A and F×D=F to find the values of two letters.
Use the clues A+H=E […]
You can mix the paints to produce different shades of pink. Explain how to find the ratio of […]
This problem is adapted from the NRICH task A Square of Numbers with permission of the University of Cambridge. All rights reserved.
Try a few of these:
Do human beings live for as long as a million hours?
If you have been alive for a million seconds, how many birthdays have you had?
What year was it one billion minutes ago?
How long would it take to count to a million […]
In the first square the boxes at the end of each row and the foot of each column give the result of multiplying the two numbers in that row or column.
Can you find 4 consecutive numbers to complete the second multiplication square in the same way?
Make up puzzles for your […]