Question

How many eight-digit numbers can be formed if the leading digit cannot be a zero

and the last number cannot be 1 or 0?

Answer 1

81 x 10^6

Explanation:

x0000000

11111111x

22222222

33333333

....................

88888888

99999999

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The first digit and 8th digit column has only 9 numbers and the rest 6 column have 10 possible numbers

9 x 9 x 10^6 = 81 x 10^6