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| Math Central | Quandaries & Queries |
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Question from Christine: Hi mi niece and I are trying to figure out what friendly factors are. An example of one of the questions: Use friendly factors to multiply the following. 8x25=. |
Hi Christine,
This is a new term to me but I can guess. I think the teacher is trying to improve her students' mental arithmetic by helping them see products or factors that they already know. In your example of 8 × 25 I know that 4 × 25 = 100 (four quarters make a dollar) and 8 = 2 × 4. Thus
8 × 25 = (2 × 4) × 25 = 2 × (4 × 25) = 2 × 100 = 200
The object is to do this in your head rather than writing it down.
I hope this helps,
Penny
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