'Double' means 'twice as much'.

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To double a number means to multiply it by 2:

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Double 1 is 2 (1 × 2 = 2)

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Double 2 is 4 (2 × 2 = 4)

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Double 3 is 6 (3 × 2 = 6), and so on.

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Half means 'split in two'.

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To half a number means to divide it by 2:

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Half of 2 is 1 (2 ÷ 2 = 1)

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Half of 4 is 2 (4 ÷ 2 = 2)

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Half of 6 is 3 (6 ÷ 2 = 3), and so on.

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