Understand a multiple of a/b as a multiple of 1/b, and use this understanding to multiply a fraction by a whole number.
Number and Operations—Fractions
Build fractions from unit fractions by applying and extending previous understandings of operations on whole numbers.
Multiply a fraction by a whole number. (Denominators are limited to 2, 3, 4, 5, 6, 8, 10, 12, and 100.)