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Dividing fractions is also easy. Did you mean summing fractions? Because, yeah, summing fractions is significantly harder than multiplying fractions, simply due
by backpropaganda 8y ago
Dividing fractions is also easy. Did you mean summing fractions? Because, yeah, summing fractions is significantly harder than multiplying fractions, simply due to pure misfortune.
- mikekchar 8y agoI may be wrong, but I think the issue is: what does it mean to divide x by 1/2? It means to multiply it by 2. We can easily understand that dividing by 2 means to split something into 2 pieces. What does it mean to split something into 1/2 pieces? Why does dividing by 1/2 mean to multiply it by 2 and does it always work that way? Can you prove it? Summation of fractions is much easier to visualise, even if it is harder to calculate.
- lagadu 8y agoInformally speaking, that can be visualised by asking "how many half pieces can you get if you have x pieces?" If I have two pieces I can break them down into 4 half pieces, which nets the same result as multiplying by two.
- alankay 8y agoThis is easy to derive if you have a little algebra, but it is shoved at kids before they can derive it, so they don't understand it (which is anti-math). The dull ones go along with it, but the brighter ones often think they are stupid. I (and independently others) have worked out visual proofs of both fraction multiplication and division for younger kids. But I mostly think that "fractions as ratios" can be left until the child is older and has more chops for derivations. The Greeks thought about these as different ways to measure intervals, and they worked out the idea of "common measure" as a good solution to dealing with these problems.