15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?
Try entering different sets of numbers in the number pyramids. How does the total at the top change?
Label this plum tree graph to make it totally magic!
If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?
My two digit number is special because adding the sum of its digits to the product of its digits gives me my original number. What could my number be?
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. . . .
Crosses can be drawn on number grids of various sizes. What do you notice when you add opposite ends?
We can show that (x + 1)² = x² + 2x + 1 by considering the area of an (x + 1) by (x + 1) square. Show in a similar way that (x + 2)² = x² + 4x + 4
Imagine a large cube made from small red cubes being dropped into a pot of yellow paint. How many of the small cubes will have yellow paint on their faces?
Make some loops out of regular hexagons. What rules can you discover?
The opposite vertices of a square have coordinates (a,b) and (c,d). What are the coordinates of the other vertices?
Find all the ways of placing the numbers 1 to 9 on a W shape, with 3 numbers on each leg, so that each set of 3 numbers has the same total.
Show that all pentagonal numbers are one third of a triangular number.
Imagine starting with one yellow cube and covering it all over with a single layer of red cubes, and then covering that cube with a layer of blue cubes. How many red and blue cubes would you need?
Jo made a cube from some smaller cubes, painted some of the faces of the large cube, and then took it apart again. 45 small cubes had no paint on them at all. How many small cubes did Jo use?
Arrange the numbers 1 to 16 into a 4 by 4 array. Choose a number. Cross out the numbers on the same row and column. Repeat this process. Add up you four numbers. Why do they always add up to 34?
Can you find a rule which connects consecutive triangular numbers?
Use the numbers in the box below to make the base of a top-heavy pyramid whose top number is 200.
Pick a square within a multiplication square and add the numbers on each diagonal. What do you notice?
Pick the number of times a week that you eat chocolate. This number must be more than one but less than ten. Multiply this number by 2. Add 5 (for Sunday). Multiply by 50... Can you explain why it. . . .
Two motorboats travelling up and down a lake at constant speeds leave opposite ends A and B at the same instant, passing each other, for the first time 600 metres from A, and on their return, 400. . . .
When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...
How could Penny, Tom and Matthew work out how many chocolates there are in different sized boxes?
Write down a three-digit number Change the order of the digits to get a different number Find the difference between the two three digit numbers Follow the rest of the instructions then try. . . .
A little bit of algebra explains this 'magic'. Ask a friend to pick 3 consecutive numbers and to tell you a multiple of 3. Then ask them to add the four numbers and multiply by 67, and to tell you. . . .
Watch these videos to see how Phoebe, Alice and Luke chose to draw 7 squares. How would they draw 100?
Some students have been working out the number of strands needed for different sizes of cable. Can you make sense of their solutions?
How many winning lines can you make in a three-dimensional version of noughts and crosses?
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?
Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...
Janine noticed, while studying some cube numbers, that if you take three consecutive whole numbers and multiply them together and then add the middle number of the three, you get the middle number. . . .
Think of two whole numbers under 10, and follow the steps. I can work out both your numbers very quickly. How?
Can you find rectangles where the value of the area is the same as the value of the perimeter?
This article explains how to make your own magic square to mark a special occasion with the special date of your choice on the top line.
A box has faces with areas 3, 12 and 25 square centimetres. What is the volume of the box?
Take any four digit number. Move the first digit to the end and move the rest along. Now add your two numbers. Did you get a multiple of 11?
Can you find a rule which relates triangular numbers to square numbers?
What are the possible dimensions of a rectangular hallway if the number of tiles around the perimeter is exactly half the total number of tiles?
The well known Fibonacci sequence is 1 ,1, 2, 3, 5, 8, 13, 21.... How many Fibonacci sequences can you find containing the number 196 as one of the terms?
Given an equilateral triangle inside an isosceles triangle, can you find a relationship between the angles?
Create some shapes by combining two or more rectangles. What can you say about the areas and perimeters of the shapes you can make?
Think of a number and follow my instructions. Tell me your answer, and I'll tell you what you started with! Can you explain how I know?
How many more miles must the car travel before the numbers on the milometer and the trip meter contain the same digits in the same order?
Can you use the diagram to prove the AM-GM inequality?
The nth term of a sequence is given by the formula n^3 + 11n . Find the first four terms of the sequence given by this formula and the first term of the sequence which is bigger than one million. . . .
Think of a number and follow the machine's instructions... I know what your number is! Can you explain how I know?
Can you explain why a sequence of operations always gives you perfect squares?
The sums of the squares of three related numbers is also a perfect square - can you explain why?
If the sides of the triangle in the diagram are 3, 4 and 5, what is the area of the shaded square?
Investigate how you can work out what day of the week your birthday will be on next year, and the year after...