A student claims: 'If a whole number is divisible by both 4 and 6, then it is divisible by 24.' Which number is a counterexample?

Answer and explanation

Correct answer: B.

  1. Step 1: are all multiples of , so they agree with the claim.
  2. Step 2: is divisible by and by but not by , so it is a counterexample. (The lowest common multiple of and is , not .)
Answer
.
Why not the others: The other numbers are multiples of and therefore satisfy the conclusion.

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