In the worst case in which you didn't take three pairs of socks of the same color, you took 2 red socks, 4 yellow socks, and 5 of each of the other colors.
That's a total of 46 socks.
Then if you take one more sock, you are sure to have 6 socks of at least one color.
So you have to take 47 socks from the drawer to be sure that you have at least three pairs of socks of the same color.
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