According to Chan, the rainbow has six colors -- red, orange, yellow, green, blue, and purple, in that order. (Yes, Chan knows that some people consider "indigo" a seventh color, but Chan thinks that's all nonsense.)

Chan wants to design a vertical tricolor (a flag with equal vertical stripes of three different colors) for Math Club, similar to this:

If Chan uses only rainbow colors, and also insists that the three colors appear in red-to-purple rainbow order from left to right (as in the example flag above), then how many different tricolors are possible?

 Jul 19, 2021

You have 6 colours in a row and you want to choose three of them


6C3 = 20

 Jul 20, 2021

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