John is bored
John was bored and decided to write down the numbers from to . How many has he written?
The answer is 108642.
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1 solution
Moderator note:
Can you explain the formula?
If the number of zeroes occurring at 10^k place till a particular number N is:
min(10^k * floor(N/10^(k+1)),N mod 10^(K+1))+(10^k-1) * floor(N/10^(k+1)))
Hence the answer is (adding the number of times zero occurs in places 10^0, 10^1, 10^2, 10^3 and 10^4):
22222 + 2222 * 10 + 222 * 100 + 22 * 1000 + 2 * 10000=108642