Posted by **Amanda** on Friday, May 25, 2007 at 9:37am.

smallest of two triangular numbers whose sum and difference are also triangular numbers

My guess would be 15.

21 - 15 = 6 and 15 + 21 = 36.

Thursday

March 23, 2017
Posted by **Amanda** on Friday, May 25, 2007 at 9:37am.

smallest of two triangular numbers whose sum and difference are also triangular numbers

My guess would be 15.

21 - 15 = 6 and 15 + 21 = 36.

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