题目内容
用你喜欢的方法算. 25×11×4 |
7.8-2.3-2.7 | 37×40+120 | ||||||||||
|
(
|
5×1.5÷(150÷15) | ||||||||||
|
x÷3=12 | 4:1=40:x. |
分析:(1)运用乘法交换律简算;
(2)根据连续减去两个数,等于减去这两个数的和简算;
(3)先把120分解成40×3,然后使用乘法分配律简算;
(4)按照从左到右的顺序计算;
(5)运用乘法分配律简算;
(6)先算小括号里面的除法,再算括号外的乘法,最后算括号外的除法;
(7)运用乘法分配律简算;
(8)根据等式的性质解方程;
(9)根据比例的性质解方程.
(2)根据连续减去两个数,等于减去这两个数的和简算;
(3)先把120分解成40×3,然后使用乘法分配律简算;
(4)按照从左到右的顺序计算;
(5)运用乘法分配律简算;
(6)先算小括号里面的除法,再算括号外的乘法,最后算括号外的除法;
(7)运用乘法分配律简算;
(8)根据等式的性质解方程;
(9)根据比例的性质解方程.
解答:解:(1)25×11×4,
=25×4×11,
=100×11,
=1100;
(2)7.8-2.3-2.7,
=7.8-(2.3+2.7),
=7.8-5,
=2.8;
(3)37×40+120,
=37×40+3×40,
=(37+3)×40,
=40×40,
=1600;
(4)
÷
×
,
=
×
,
=
;
(5)(
-
)×12,
=
×12-
×12,
=4-3,
=1;
(6)5×1.5÷(150÷15),
=5×1.5÷10,
=7.5÷10,
=0.75;
(7)
×
+
×
,
=
×(
+
),
=
×1,
=
;
(8)x÷3=12,
解:x÷3×3=12×3,
x=36;
(9)4:1=40:x,
解:4x=40×1,
4x=40,
4x÷4=40÷4,
x=10.
=25×4×11,
=100×11,
=1100;
(2)7.8-2.3-2.7,
=7.8-(2.3+2.7),
=7.8-5,
=2.8;
(3)37×40+120,
=37×40+3×40,
=(37+3)×40,
=40×40,
=1600;
(4)
5 |
8 |
1 |
4 |
3 |
5 |
=
5 |
2 |
3 |
5 |
=
3 |
2 |
(5)(
1 |
3 |
1 |
4 |
=
1 |
3 |
1 |
4 |
=4-3,
=1;
(6)5×1.5÷(150÷15),
=5×1.5÷10,
=7.5÷10,
=0.75;
(7)
7 |
12 |
1 |
3 |
2 |
3 |
7 |
12 |
=
7 |
12 |
1 |
3 |
2 |
3 |
=
7 |
12 |
=
7 |
12 |
(8)x÷3=12,
解:x÷3×3=12×3,
x=36;
(9)4:1=40:x,
解:4x=40×1,
4x=40,
4x÷4=40÷4,
x=10.
点评:此题考查了运算定律与运算性质,四则混合运算以及解方程.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.
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