100. Factor Venn

In the last post I discussed Prime Factor Decomposition, using factor trees. I also use this method for Highest Common Factor (HCF) and Lowest Common Multiple (LCM). The difference is you need two different coloured pens and a Venn diagram:

Factorise your first number

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Factorise your second number

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Draw and label an empty Venn diagram in appropriate colours

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Fill in the common factors

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Fill in the rest

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HCF: Multiply the overlapping area

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LCM: Multiply everything

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Review
This method is great for visual learners who want to see where the numbers come from. You can also quickly spot where they have made a mistake in a calculation.

Challenge
This method also works for three numbers – just use three colours and three circles!

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