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利用简便方法计算.3.74×2.85+8.15×3.74-3.74;99.99×0.8+11.11×2.8;31.4×0.68+314×0.032;3.46×(2.8-1.3)+1.5×1.54;22.8×98+45.6;999.9×0.28+0.6666×80;5.2×11111+66666×0.8;20.05×39+200.5×4.1+40×10.025

题目详情
利用简便方法计算.
3.74×2.85+8.15×3.74-3.74;    
99.99×0.8+11.11×2.8;
31.4×0.68+314×0.032;    
3.46×(2.8-1.3)+1.5×1.54;
22.8×98+45.6;    
999.9×0.28+0.6666×80;
5.2×11111+66666×0.8;    
20.05×39+200.5×4.1+40×10.025.
▼优质解答
答案和解析
(1)3.74×2.85+8.15×3.74-3.74
=3.74×(2.85+8.15-1)
=3.74×10
=37.4;

(2)99.99×0.8+11.11×2.8
=11.11×7.2+11.11×2.8
=11.11×(7.2+2.8)
=11.11×10
=111.1;

(3)31.4×0.68+314×0.032
=314×0.068+314×0.032
=314×(0.068+0.032)
=314×0.1
=31.4;

(4)3.46×(2.8-1.3)+1.5×1.54
=3.46×1.5+1.5×1.54
=(3.46+1.54)×1.5
=5×1.5
=7.5;

(5)22.8×98+45.6
=22.8×98+22.8×2
=22.8×(98+2)
=22.8×100
=2280;

(6)999.9×0.28+0.6666×80
=3333×0.084+3333×0.016
=3333×(0.084+0.016)
=3333×0.1
=333.3;

(7)5.2×11111+66666×0.8
=5.2×11111+11111×4.8
=(5.2+4.8)×11111
=10×11111
=111110;

(8)20.05×39+200.5×4.1+40×10.025
=200.5×3.9+200.5×4.1+40×10.025
=(3.9+4.1)×200.5+40×10.025
=8×200.5+40×10.025
=8×200.5+2×200.5
=(8+2)×200.5
=10×200.5
=2005.