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