3. B 4.C 四、准确计算 1. 80 7 720 90 240 29 120 40 2. 3.计算下面各题,能简算的要简算。 75×46+46×25 =(75+25)×46 =100×46 =4600
4500÷25÷4 =4500÷(25×4) =4500÷100 =45
1200-72×25÷24 =1200-72÷24×25 =1200-3×25 =1200-75 =1125
994-129-71 =994-(129+71) =994-200 =794
14×36-650÷26 =504-25 =479
47×99+47 =47×(99+1) =47×100 =4700 |