When you're multiplying fractions by an integer (or a whole number) you multiply the numerator of the fraction by the whole number, whilst the denominator of the fraction stays the same. Think about ...

“Who would draw a picture to divide 2/3 by 3/4?” asked Marina Ratner, a professor emerita of mathematics at the University of California at Berkeley, in a recent Wall Street Journal opinion piece.

Multiplying and dividing whole numbers by numbers greater than 0 and less than 1 can be broken into a whole number calculation followed by multiplying or dividing by a power of 10, for example 10, 100 ...