用简便方法计算
①4.85×3﹣3.6+6.15×3 ②0.025×999×2.8×40÷2
③(﹣)×23+25÷71+15÷23 ④9.81×0.1+0.5×98.1+0.049×981
⑤1000+999﹣998﹣997+996+995﹣994﹣993+…+104+103﹣102﹣101.
用简便方法计算
①4.85×3﹣3.6+6.15×3 ②0.025×999×2.8×40÷2
③(﹣)×23+25÷71+15÷23 ④9.81×0.1+0.5×98.1+0.049×981
⑤1000+999﹣998﹣997+996+995﹣994﹣993+…+104+103﹣102﹣101.