11 and 18
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In every 100 there are 10 numbers that have a units digit of 2 and 10 with 7, making 2 with 2 or 7. Between 0 and 1000 there are 10 hundreds, making 10 × 20 = 200 such numbers. BUT 2 and 7 are less than 10, so there are two less such numbers, making 200 - 2 = 198 such numbers.
21
It is: 2*3*3*11 = 198
There are 28706 such combinations. 5456 of these comprise three 2-digit numbers, 19008 comprise two 2-digit numbers and two 1-digit numbers, 4158 comprise one 2-digit number and four 1-digit numbers and 84 comprise six 1-digit numbers.
The answer will depend on how many digits there are in each of the 30 numbers. If the 30 numbers are all 6-digit numbers then the answer is NONE! If the 30 numbers are the first 30 counting numbers then there are 126 combinations of five 1-digit numbers, 1764 combinations of three 1-digit numbers and one 2-digit number, and 1710 combinations of one 1-digit number and two 2-digit numbers. That makes a total of 3600 5-digit combinations.