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International Contests
Nordic
2011 Nordic
1
1
Part of
2011 Nordic
Problems
(1)
Can a number plus its reverse have only odd digits
Source: Nordic MO 2011 Q1
4/21/2013
When
a
0
,
a
1
,
…
,
a
1000
a_0, a_1, \dots , a_{1000}
a
0
,
a
1
,
…
,
a
1000
denote digits, can the sum of the
1001
1001
1001
-digit numbers
a
0
a
1
⋯
a
1000
a_0a_1\cdots a_{1000}
a
0
a
1
⋯
a
1000
and
a
1000
a
999
⋯
a
0
a_{1000}a_{999}\cdots a_0
a
1000
a
999
⋯
a
0
have odd digits only?
number theory unsolved
number theory