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From module Arithmetic and Number Theory Basics
10−9+8−7+6−5+4−3+2−11−2+3−4+5−6+7−8+9=\frac{10-9+8-7+6-5+4-3+2-1}{1-2+3-4+5-6+7-8+9}=1−2+3−4+5−6+7 −8+910−9+8−7+6−5+4−3+2−1=
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