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Double counting (proof technique)

math Maturity 7-9

You can count things in two ways. You might count rows first. Then you can count columns. It is still the same group. Both ways give the same answer. This helps us know we are right. Can you find two ways to count your toys?

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File:Cayley's formula 2-4.svg
Cayley's formula 2-4.svg
File:Graph.tree. Cayley's formula.png
Graph.tree. Cayley's formula.png
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📚 Content adapted from Wikipedia | Readability: FK 11.3 | Vital Level 5