计算1000-1-2-3-4-…-20
原式=1000-(1+2+3+4+5+…+20)
=1000-
=1000-210
=790.
2025-10-15
2025-09-16
2025-08-21
2025-07-25
2025-07-21
2025-07-16
2025-07-15