The conversation between human and AI assistant.
Find the sum of all the three digit numbers formed by using the digits 2, 3, 4, 5 and 6, without repetition?
How did you calculate that?
I used the formula (n*(n-1)/2)*(a+b+c+d+e), where n is the number of digits used (in this case, 5), and a, b, c, d, and e are the digits used (2, 3, 4, 5, and 6). Plugging in the values, we get (5*(5-1)/2)*(2+3+4+5+6) = 104*20 = 2,080. Then we subtract the sum of the two digit numbers formed by using the digits 2, 3, 4, 5, and 6 without repetition, which is (n*(n-1)/2)*(a+b+c+d), and we get 2,080 - (4*(4-1)/2)*(2+3+4+5) = 2,080 - 372 = 1,708.