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2
times of digit 1 in N = 9 + 99 + 999 + ... +999...9 (2018 Auckland MO S2)
times of digit 1 in N = 9 + 99 + 999 + ... +999...9 (2018 Auckland MO S2)
Source:
November 15, 2021
number theory
Digits
Problem Statement
Consider a positive integer,
N
=
9
+
99
+
999
+
.
.
.
+
999...9
⏟
2018
N = 9 + 99 + 999 + ... +\underbrace{999...9}_{2018}
N
=
9
+
99
+
999
+
...
+
2018
999...9
. How many times does the digit
1
1
1
occur in its decimal representation?
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