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2020 BMT Fall
11
2020 BMT Team 11
2020 BMT Team 11
Source:
January 9, 2022
number theory
Problem Statement
Compute
∑
x
=
1
999
gcd
(
x
,
10
x
+
9
)
\sum^{999}_{x=1}\gcd (x, 10x + 9)
∑
x
=
1
999
g
cd
(
x
,
10
x
+
9
)
.
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