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Problems
Contests
National and Regional Contests
China Contests
China Northern MO
2009 China Northern MO
8
8
Part of
2009 China Northern MO
Problems
(1)
sum of digits of number N is 209 and 209 | N
Source: China Northern MO 2009 p8 CNMO
12/12/2020
Find the smallest positive integer
N
N
N
satisfies : 1 .
209
209
209
ā
N
N
N
2 .
S
(
N
)
=
209
S (N) = 209
S
(
N
)
=
209
( # Here
S
(
m
)
S(m)
S
(
m
)
means the sum of digits of number
m
m
m
)
number theory
sum of digits
divides