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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?

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In 15 years' time my age will be the square of my age 15 years ago. Can you work out my age, and when I had other special birthdays?

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Many numbers can be expressed as the difference of two perfect squares. What do you notice about the numbers you CANNOT make?

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There are lots of different methods to find out what the shapes are worth - how many can you find?

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Think of two whole numbers under 10, and follow the steps. I can work out both your numbers very quickly. How?

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Polygons drawn on square dotty paper have dots on their perimeter (p) and often internal (i) ones as well. Find a relationship between p, i and the area of the polygons.

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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?

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Choose four consecutive whole numbers. Multiply the first and last numbers together. Multiply the middle pair together. What do you notice?

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Try entering different sets of numbers in the number pyramids. How does the total at the top change?

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When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...

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Think of a number and follow the machine's instructions... I know what your number is! Can you explain how I know?

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Can you find the values at the vertices when you know the values on the edges?

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How many pairs of numbers can you find that add up to a multiple of 11? Do you notice anything interesting about your results?

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Can you find a way to identify times tables after they have been shifted up or down?

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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?

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Here is a machine with four coloured lights. Can you make two lights switch on at once? Three lights? All four lights?

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Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?

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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?

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Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?

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Can you find the values at the vertices when you know the values on the edges of these multiplication arithmagons?

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Imagine we have four bags containing numbers from a sequence. What numbers can we make now?

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Where should you start, if you want to finish back where you started?

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In this interactivity each fruit has a hidden value. Can you deduce what each one is worth?

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The Number Jumbler can always work out your chosen symbol. Can you work out how?