How many positive integers less than 1000000 have the sum of their equal to 7?

To find the number of positive integers less than 1,000,000 whose digits sum to 7, we can use the "stars and bars" combinatorial method. We consider a six-digit representation (including leading zeros) of numbers, which can be expressed as (d_1 + d_2 + d_3 + d_4 + d_5 + d_6 = 7), where (0 \leq d_i \leq 9). The number of non-negative integer solutions to this equation is given by the formula (\binom{n + k - 1}{k - 1}), where (n) is the sum (7) and (k) is the number of digits (6). Thus, the result is (\binom{7 + 6 - 1}{6 - 1} = \binom{12}{5} = 792). Therefore, there are 792 positive integers less than 1,000,000 with digits summing to 7.