Which of the following CANNOT be the HCF and LCM of two numbers?

HCF 18, LCM 390Correct answerYour answerHCF 15, LCM 225Correct answerYour answerHCF 8, LCM 96Correct answerYour answerHCF 12, LCM 84Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

The HCF always divides the LCM exactly.
$84 \div 12 = 7$ , $225 \div 15 = 15$ , $96 \div 8 = 12$ : all whole numbers.
$390 \div 18 \approx 21.67$ , not a whole number, so HCF 18 and LCM 390 is impossible.

Concept: The HCF must divide the LCM
Typical timeTypical: 60 s
Your timeYours: —

The rule this testsFinding HCF and LCM

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Ten questions from HCF & LCM, at your own pace.

Which of the following CANNOT be the HCF and LCM of two numbers?

Explanation