What is the result when 2/3 is subtracted from 1?

• A. 1/3
• B. 2/3
• C. 0
• D. 1

Answer: (A)

Subtracting fractions with a whole works best by making the whole have the same denominator as the fraction being subtracted. Turn 1 into 3/3, then subtract 2/3: 3/3 − 2/3 = 1/3.

A helpful picture: a pizza sliced into three equal parts. If you eat two parts, one part remains of the whole three parts, which is one-third.

Other results would come from subtracting different amounts: removing only one-third leaves two-thirds, removing the entire amount would leave zero, and removing nothing would leave one. But with two-thirds removed, the leftover is one-third.