用简便方法计算. 6.2+5.12+3.8 35+9.2-5.35 13.7-8.9-1.1 3.63-1.25+17.37-8.75 78×45+22×45 56×101.
(1)6.2+5.12+3.8
=6.2+3.8+5.12
=10+5.12
=15.12;
(2)35+9.2-5.35
=44.2-5.35
=38.85;
(3)13.7-8.9-1.1
=13.7-(8.9+1.1)
=13.7-10
=3.7;
(4)3.63-1.25+17.37-8.75
=(3.63+17.37)-(1.25+8.75)
=21-10
=11;
(5)78×45+22×45
=(78+22)×45
=100×45
=4500;
(6)56×101
=56×(100+1)
=56×100+1×56
=5600+56
=5656.
=6.2+3.8+5.12
=10+5.12
=15.12;
(2)35+9.2-5.35
=44.2-5.35
=38.85;
(3)13.7-8.9-1.1
=13.7-(8.9+1.1)
=13.7-10
=3.7;
(4)3.63-1.25+17.37-8.75
=(3.63+17.37)-(1.25+8.75)
=21-10
=11;
(5)78×45+22×45
=(78+22)×45
=100×45
=4500;
(6)56×101
=56×(100+1)
=56×100+1×56
=5600+56
=5656.
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