Question 1119742: How many times will the digit '1' appear if we write
all whole numbers from 1 to 9999? Found 2 solutions by Alan3354, ikleyn:Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website! How many times will the digit '1' appear if we write
all whole numbers from 1 to 9999?
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It's just a matter of counting them, there's no succinct solution.
From 1 to 99 ---> 9 + 1 for the eleven --> 10
etc.
If you write all 4-digit numbers from 0 to 9999 in column
0000
0001
0002
0003
. . .
9999
replacing/filling by zeroes the leading positions in 1-digit, 2-digit and 3-digit numbers,
you will have 10000 = numbers (= lines), each containing 4 digits.
So, the total number of positions (place-holders) for digits in these lines is .
Now, it is OBVIOUS ( ! attention ! - It is the key idea of the solution !), each digit from 0 to 9 does appear equal number of times
in these place-holders.
Therefore, each digit (including '1') appears = = 4000 times.
Answer. The digit '1' appears 4000 times if we write all whole numbers from 1 to 9999.
