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用简便方法计算.4.02-3.5+0.987.08-0.74-1.260.81×99+0.8125×(85+85+85+85)

题目详情
用简便方法计算.
4.02-3.5+0.98
7.08-0.74-1.26 
0.81×99+0.81                   
25×(85+85+85+85)
▼优质解答
答案和解析
(1)4.02-3.5+0.98,
=4.02+0.98-3.5,
=5-3.5,
=1.5;
(2)7.08-0.74-1.26,
=7.08-(0.74+1.26),
=7.08-2,
=5.08;
(3)0.81×99+0.81,
=0.81×(99+1),
=0.81×100,
=81;
(4)25×(85+85+85+85),
=25×85×4,
=85×(25×4),
=85×100,
=8500.