Fractions and Ratio: Parts of a Whole

Methods in this video

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1. 1

   Same whole: count the parts left

   ▶ 0:56

   When to use it: The fractions refer to the same whole, or to several identical wholes. Find what is left, how much more is needed, an overlap, or the whole from a known share.

   • Ask what each fraction is a fraction of. Keep each small part the same size.
   • For what is left, subtract used parts. For how many more, subtract what is already there from the target.
   • Divide a known share by its number of parts. Then count the parts the question asks for.
2. 2

   Split only the part that is left; work back one step at a time

   ▶ 4:11

   When to use it: A fraction refers to a remainder or an earlier share. Fractions and fixed amounts may be taken in stages. Find a final share, the starting amount, or an amount used along the way.

   • Name the part each fraction belongs to. Split only that part.
   • Find the fraction left before working back. Undo the last stage first, including any fixed amount.
   • Label each amount. If asked what was spent, rebuild the balance first, then subtract it from the amount before that step.