Question 1011408
How to find total no of 9 digit number?
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If leading zeroes are allowed, eg 000000001, there are 10^9 of them.
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If not, they're from
100,000,000 to 999,999,999
999,999,999 - 100,000,000 = 899,999,999
--> 900,000,000 of them