Count the digits up to 2018
Number Theory
Level
2
How many total digits are there from ?
Note: You are counting the number of digits, not the numbers themselves!
The answer is 6965.
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1 solution
Let a , b , c and d be the numbers of one, two, three and four digit numbers. my formula is:
1 a + 2 b + 3 c +4 d = total number of digits.
For our problem, we get:
1(9) + 2(90) + 3(900) + 4(1019) = 6965