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· inv-2
Invariants & Monovariants · Invariant quantities
Olympiad classic
●●●●○ 8/10
~8 min
⏱ 0:00
The numbers
1
,
2
,
…
,
10
1, 2, \ldots, 10
1
,
2
,
…
,
10
are on a board. A move erases two numbers
a
,
b
a, b
a
,
b
and writes
a
+
b
+
a
b
a + b + ab
a
+
b
+
ab
. After nine moves one number remains. What are its last three digits?
invariant
product
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Hint 1 of 3
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