This challenge focuses on finding the sum and difference of pairs of two-digit numbers.
Try adding together the dates of all the days in one week. Now multiply the first date by 7 and add 21. Can you explain what happens?
This task follows on from Build it Up and takes the ideas into three dimensions!
In a Magic Square all the rows, columns and diagonals add to the 'Magic Constant'. How would you change the magic constant of this square?
Watch this animation. What do you notice? What happens when you try more or fewer cubes in a bundle?
Find the sum and difference between a pair of two-digit numbers. Now find the sum and difference between the sum and difference! What happens?
We can arrange dots in a similar way to the 5 on a dice and they usually sit quite well into a rectangular shape. How many altogether in this 3 by 5? What happens for other sizes?
Find the sum of all three-digit numbers each of whose digits is odd.
An investigation that gives you the opportunity to make and justify predictions.
This challenge, written for the Young Mathematicians' Award, invites you to explore 'centred squares'.
This challenge encourages you to explore dividing a three-digit number by a single-digit number.
Can you find all the ways to get 15 at the top of this triangle of numbers? Many opportunities to work in different ways.
Put the numbers 1, 2, 3, 4, 5, 6 into the squares so that the numbers on each circle add up to the same amount. Can you find the rule for giving another set of six numbers?
Sweets are given out to party-goers in a particular way. Investigate the total number of sweets received by people sitting in different positions.
Only one side of a two-slice toaster is working. What is the quickest way to toast both sides of three slices of bread?
Ben’s class were cutting up number tracks. First they cut them into twos and added up the numbers on each piece. What patterns could they see?
Tom and Ben visited Numberland. Use the maps to work out the number of points each of their routes scores.
How many ways can you find to do up all four buttons on my coat? How about if I had five buttons? Six ...?
What can you say about these shapes? This problem challenges you to create shapes with different areas and perimeters.
What happens if you join every second point on this circle? How about every third point? Try with different steps and see if you can predict what will happen.
In this problem we are looking at sets of parallel sticks that cross each other. What is the least number of crossings you can make? And the greatest?
Strike it Out game for an adult and child. Can you stop your partner from being able to go?
Can you put the numbers 1-5 in the V shape so that both 'arms' have the same total?
Investigate the sum of the numbers on the top and bottom faces of a line of three dice. What do you notice?
Can you make dice stairs using the rules stated? How do you know you have all the possible stairs?
Got It game for an adult and child. How can you play so that you know you will always win?
Polygonal numbers are those that are arranged in shapes as they enlarge. Explore the polygonal numbers drawn here.
What happens when you round these three-digit numbers to the nearest 100?
Can you see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?
In how many different ways can you break up a stick of 7 interlocking cubes? Now try with a stick of 8 cubes and a stick of 6 cubes.
What happens when you round these numbers to the nearest whole number?
Can you continue this pattern of triangles and begin to predict how many sticks are used for each new "layer"?
Use two dice to generate two numbers with one decimal place. What happens when you round these numbers to the nearest whole number?
While we were sorting some papers we found 3 strange sheets which seemed to come from small books but there were page numbers at the foot of each page. Did the pages come from the same book?
Find out what a "fault-free" rectangle is and try to make some of your own.
Compare the numbers of particular tiles in one or all of these three designs, inspired by the floor tiles of a church in Cambridge.
How many different journeys could you make if you were going to visit four stations in this network? How about if there were five stations? Can you predict the number of journeys for seven stations?
Use your addition and subtraction skills, combined with some strategic thinking, to beat your partner at this game.
Can you explain the strategy for winning this game with any target?
Find a route from the outside to the inside of this square, stepping on as many tiles as possible.
Place the numbers from 1 to 9 in the squares below so that the difference between joined squares is odd. How many different ways can you do this?
How many pairs of numbers can you find that add up to a multiple of 11? Do you notice anything interesting about your results?
Are these statements always true, sometimes true or never true?
Find some examples of pairs of numbers such that their sum is a factor of their product. eg. 4 + 12 = 16 and 4 × 12 = 48 and 16 is a factor of 48.
List any 3 numbers. It is always possible to find a subset of adjacent numbers that add up to a multiple of 3. Can you explain why and prove it?
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
How many centimetres of rope will I need to make another mat just like the one I have here?
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.
The number of plants in Mr McGregor's magic potting shed increases overnight. He'd like to put the same number of plants in each of his gardens, planting one garden each day. How can he do it?
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.