题目内容
(1)
(2)
(3)35.79×37+35.79×82-357.9×1.9
(4)
.
解:(1)
÷(
+
×5),
=
÷(
+1),
=
÷
,
=
×
,
=
;
(2)
×
-
÷1.25,
=
×
-
÷
,
=
×
-
×
,
=(
-
)×
,
=
×
,
=
;
(3)35.79×37+35.79×82-357.9×1.9,
=35.79×37+35.79×82-35.79×19,
=35.79×(37+82-19),
=35.79×100,
=3579;
(4)[(0.875-
)×0.25]÷
,
=[(
-
)×
]÷
,
=[
×
]÷
,
=
×
×
,
=
.
分析:(1)先算括号内的乘法,再算括号内的加法,最后算括号外的除法;
(2)把小数化为分数,把除法变为乘法,运用乘法分配律简算;
(3)根据数字特点,通过数字转化,运用乘法分配律简算;
(4)把小数化为分数,先算小括号内的,原式变为
×
×
,约分计算.
点评:此题考查了分数的四则混合运算,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.
=
=
=
=
(2)
=
=
=(
=
=
(3)35.79×37+35.79×82-357.9×1.9,
=35.79×37+35.79×82-35.79×19,
=35.79×(37+82-19),
=35.79×100,
=3579;
(4)[(0.875-
=[(
=[
=
=
分析:(1)先算括号内的乘法,再算括号内的加法,最后算括号外的除法;
(2)把小数化为分数,把除法变为乘法,运用乘法分配律简算;
(3)根据数字特点,通过数字转化,运用乘法分配律简算;
(4)把小数化为分数,先算小括号内的,原式变为
点评:此题考查了分数的四则混合运算,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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例:
3÷3+3-3=1 33÷33=1(1)
|
① 3 3 3 3=1 |
② 3 3 3 3=2 |
|
③ 3 3 3 3=3 |
④ 3 3 3 3=4 |
|
⑤ 3 3 3 3=5 |
⑥ 3 3 3 3=6 |
|
⑦ 3 3 3 3=7 |
⑧ 3 3 3 3=8 |
|
⑨ 3 3 3 3=9 |
⑩ 3 3 3 3=10 |
(2)
|
① 3 3 3 3=1 |
② 3 3 3 3=2 |
|
③ 3 3 3 3=3 |
④ 3 3 3 3=4 |
|
⑤ 3 3 3 3=5 |
⑥ 3 3 3 3=6 |
|
⑦ 3 3 3 3=7 |
⑧ 3 3 3 3=8 |
|
⑨ 3 3 3 3=9 |
⑩ 3 3 3 3=10 |
|
① 3 3 3 3=1 |
② 3 3 3 3=2 |
|
③ 3 3 3 3=3 |
④ 3 3 3 3=4 |
|
⑤ 3 3 3 3=5 |
⑥ 3 3 3 3=6 |
|
⑦ 3 3 3 3=7 |
⑧ 3 3 3 3=8 |
|
⑨ 3 3 3 3=9 |
⑩ 3 3 3 3=10 |