This math skill teaches how to calculate the number of different ways to select a subset of tiles from a larger set using combinations. Specifically, it explains using binomial coefficients or "n choose k" notation, using factorials to determine the number of unique combinations possible when order does not matter.
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Counting ways to pick N tiles from M total tiles
Test your understanding of total outcome counting with letters by practicing it! Work through the below exercises to use it in practice.
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How many different ways can we draw 2 tiles from this set of 6 letter tiles?
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To phrase this in a way that will help find the right formula, we are are looking to pick 2 from 6 in any order.
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So that's 6 choose 2, or, in binomial notation, 6 over 2 in brackets
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The factorial equation for 6 choose 2 is 6 factorial, divided by, 2 factorial times 6 - 2 factorial.
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If we calculate that out, that's 15 unique ways to pick 2 letter tiles if order doesn't matter