(1+3+5+···+1999)—(2+4+6+···+1988) = = =
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(1+3+5+···+1999)—(2+4+6+···+1988)===(1+3+5+···+1999)—(2+4+6+···+1988)===(1+3+5+···+1999)—(2+4+6+···+
(1+3+5+···+1999)—(2+4+6+···+1988) = = =
(1+3+5+···+1999)—(2+4+6+···+1988) = = =
(1+3+5+···+1999)—(2+4+6+···+1988) = = =
用等差公式做
【1*1000+(999*1000/2)*2】-【2*994+（994*993/2)*2】
结果自己按计算器吧...
(1+3+5+···+1999)—(2+4+6+···+1988) = = =
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