15.1×2+2×3+3×4+……+99×100
16.5×6+6×7+7×8+……+19×20
17.1×3+2×4+3×5+……+48×50
18.20×22+21×23+22×24+……+98×100
19.(2+0.38+0.49)×(0.38+0.49+0.5)-(2+ 0.38+0.49+0.5)×(0.38+0.49)
20.(0.123+0.234+0.345)×(0.234+0.345+0.456)-(0.123+0.234+0.345+0.456)×(0.234+0.345)
聯(lián)系客服