Question

How many seven-digit numbers are there when 0 and 8 cannot be the leading number?

There are_____such seven-digit numbers.

Answer 1

With the restrictions that 0 or 8 cannot be the leading digit, the leading digit can be one of [1, 2, 3, 4, 5, 6, 7, 9] = 8 choices.

The other six digits can be one of [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] = 10 choices each.

Therefore, there are:

8*10*10*10*10*10*10 = 8*10^6 = 8,000,000 7-digit numbers under the given restrictions.

Explanation:

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