Best Answer

First you express the numbers as the product of their prime factors:

28 = 2x2x7

21 = 3x7

Next you find the HCF. In this case, the HCF is 7. Finally, you multiply the numbers together and divide by the HCF. 28x21/7 = 84

Therefore the LCM of 28 and 21 is 84.

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โˆ™ 2012-02-26 16:04:14
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Q: How do you find LCM of 28 and 21?
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