问题
解答题
1000-10-20-30-…-100.
答案
1000-10-20-30-…-100,
=1000-(10+20+…+100),
=1000-(10+100)×10÷2,
=1000-550,
=450.
1000-10-20-30-…-100.
1000-10-20-30-…-100,
=1000-(10+20+…+100),
=1000-(10+100)×10÷2,
=1000-550,
=450.