2017 AIME I Problems/Problem 3
Contents
Problem 3
For a positive integer , let
be the units digit of
. Find the remainder when
is divided by
.
Solution
We see that appears in cycles of
and the cycles are
adding a total of
each cycle.
Since
, we know that by
, there have been
cycles and
has been added. This can be discarded as we're just looking for the last three digits.
Adding up the first
of the cycle of
, therefore we see that the answer is
.
Video Solution
https://youtu.be/BiiKzctXDJg ~Maths_Is_Hard
See Also
2017 AIME I (Problems • Answer Key • Resources) | ||
Preceded by Problem 2 |
Followed by Problem 4 | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 | ||
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