| 计算下列各题,能简算的要简算. 3.75× + ×1.25 | 0.25×1.25×32 |
+ +1 +8![]() | ( + + )÷![]() |
| 5.36-1.86-3.14 | 6.8×8+3.5×8-44. |
+
×1.25,=(3.75+1.25)×
,=5×
,=3;
(2)0.25×1.25×32,
=0.25×1.25×8×4,
=(0.25×4)×(1.25×8),
=1×10,
=10;
(3)
+
+1
+8
,=(
+8
)+(
+1
),=9+2,
=11;
(4)(
+
+
)÷
,=(
+
+
)×12,=
×12+
×12+
×12,=3+10+2,
=15;
(5)5.36-1.86-3.14,
=5.36-(1.86+3.14),
=5.36-5,
=0.36;
(6)6.8×8+3.5×8-44,
=(6.8+3.5)×8-44,
=10.3×8-44,
=82.4-44,
=38.4.
分析:(1)(6)运用乘法分配律简算;
(2)先把32分解成4×8,再运用乘法结合律简算;
(3)运用加法交换了和结合律简算;
(4)先把除法变成乘法,再运用乘法分配律简算;
(5)根据连续减去两个数,等于减去这两个数的和简算.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.