Q8 PERMUTATION AND COBINATION

How many numbers greater than 0 and less than a million can be formed with the digits of 0, 7 and 8?

For a number to be greater than zero it must have at least a single non zero digit.

For a number to be less than a million it can have a maximum of 6 digits.

Now, we have 6 places, each places can be filled with 3 digits(0,7,8).

So we can have numbers, 3*3*3*3*3*3 = 3^6

But in this one pattern is all digits being filled with zero.

Final answer is 3^6-1

The total numbers are 729-1 = 728 

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