How many sets of three in forty-five?

To calculate the number of sets of three in forty-five, we use the combination formula, which is nCr = n! / r!(n-r)!. In this case, n = 45 and r = 3. Plugging these values into the formula, we get 45C3 = 45! / 3!(45-3)! = 45! / 3!42!. Simplifying further, we get 45C3 = (45 x 44 x 43) / (3 x 2 x 1) = 14,190. Therefore, there are 14,190 sets of three in forty-five.