#### Answer

$462$

#### Work Step by Step

Factor each number completely to obtain:
$42= 2\cdot 3\cdot 7
\\66 = 2 \cdot 3 \cdot 11$
The different factors that appear in the prime factorization of the given numbers are 2, 3, 7, and 11.
The maximum number of times that each unique factor appears in the factorization is:
For 2: once
For 3: once
For 7: once
For 11: once
The least common multiple will have one 2, one 3, one 7, and one 11.
Thus, the least common multiple of the given numbers is:
$=2 \cdot 3\cdot 7 \cdot 11
\\= 462$