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简介:
一、加法简便计算
2.5+3.8+7.5
=(2.5+7.5)+3.8
=10+3.8
=13.8 4.36+5.7+0.64
=(4.36+0.64)+5.7
=5+5.7
=10.7
9.1+6.32+0.9+1.68
=(9.1+0.9)+(6.32+1.68)
=10+8
=18 12.8+5.25+7.2+4.75
=(12.8+7.2)+(5.25+4.75)
=20+10
=30
3.6+8.74+6.4+1.26
=(3.6+6.4)+(8.74+1.26)
=10+10
=20 7.5+2.5-7.5+2.5
=(7.5-7.5)+(2.5+2.5)
=0+5
=5
二、减法简便计算