Friday, February 26, 2010

90

90 = 2 x 32 x 5.

90 has a representation as a sum of two squares: 90 = 32 + 92.

90 is the smallest number that has six representations as a sum of four positive squares: 90 = 12 + 22 + 22 + 92 = 12 + 22 + 62 + 72 = 12 + 32 + 42 + 82 = 22 + 52 + 52 + 62 = 32 + 32 + 62 + 62 = 32 + 42 + 42 + 72.

90 is 66 in base 14.

As a compass direction, 90 degrees corresponds to east.

Source: WolframAlpha

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