Question

（2011?富源縣模擬）直接寫出結(jié)果（近似值符號的要求估算）．

4 5 - 2 3 + 1 5 =	3 4 × 1 3 ÷ 3 4 =	1 3 - 1 4 =	1 3 + 1 5 + 2 3 + 4 5 =	1-0.74=	1.25×3×8=
249-198=	238÷72≈	115+178≈	4.05-2.8-0.2=	0.9×99+0.9=．

Answer 1

分析：根據(jù)整數(shù)、分?jǐn)?shù)的加減乘除法的計算法則進(jìn)行解答即可，能簡算的要簡算，整數(shù)的估算，把接近整十、整百的數(shù)看成整十、整百數(shù)進(jìn)行計算，

解答：解：

4 5 - 2 3 + 1 5 = 1 3	3 4 × 1 3 ÷ 3 4 = 1 3	1 3 - 1 4 = 1 12	1 3 + 1 5 + 2 3 + 4 5 =2	1-0.74=0.26	1.25×3×8=30
249-198=51	238÷72≈3	115+178≈300	4.05-2.8-0.2=1.05	0.9×99+0.9=90

點評：查看了整數(shù)、分?jǐn)?shù)加減乘除法的口算能力及估算方法．