How many seven-digit numbers less than 1,048,000 can be made using the digits 0,1,4,6,7,8, and 9? Make a list of possible ways to represent your seven-digit numbers.

Answer 1

The constraints are:
1. the number has to have 7 digits (i.e. the first digit cannot be zero)
2. the resulting number cannot be more than 104800.

Starting from the left-most digit, ask yourself which digits will fit the constraints.

Continue this way for the remaining digits. If there is more than one choice, make a list of each possibility, and work on each separately.

Answer 2

2x9x9x9x9x9x9