一、口算。
$187×20= $
$305-25= $
$204×5= $
$470+70= $
$21×8= $
$214+76= $
$800-12= $
$256÷4= $
$72×6= $
$505÷5= $
$180×5= $
$900÷60= $
$545+55= $
$3200÷16= $
$34+28= $
$810÷45= $
$27×40= $
$303×3= $
$350-35= $
$217+733= $
$920÷4= $
$43×30= $
$750÷25= $
$360÷15= $
$187×20= $
3740
$305-25= $
280
$204×5= $
1020
$470+70= $
540
$21×8= $
168
$214+76= $
290
$800-12= $
788
$256÷4= $
64
$72×6= $
432
$505÷5= $
101
$180×5= $
900
$900÷60= $
15
$545+55= $
600
$3200÷16= $
200
$34+28= $
62
$810÷45= $
18
$27×40= $
1080
$303×3= $
909
$350-35= $
315
$217+733= $
950
$920÷4= $
230
$43×30= $
1290
$750÷25= $
30
$360÷15= $
24
答案
一、3740 280 1020 540 168 290 788 64 432 101 900 15 600 200 62 18 1080 909 315 950 230 1290 30 24
二、计算下面各题,怎样简便就怎样计算。
$185×38+15×38$
$478-145÷5×6$
$50+129×28-42$
$1000-(560÷7+99)$
$85×25×2×4$
$115×(244-220)÷40$
$185×38+15×38$
$478-145÷5×6$
$50+129×28-42$
$1000-(560÷7+99)$
$85×25×2×4$
$115×(244-220)÷40$
答案
二、7600 304 3620 821 17000 69
解析
185×38+15×38
=(185+15)×38
=200×38
=7600
478-145÷5×6
=478-29×6
=478-174
=304
50+129×28-42
=50+3612-42
=3662-42
=3620
1000-(560÷7+99)
=1000-(80+99)
=1000-179
=821
85×25×2×4
=85×2×(25×4)
=170×100
=17000
115×(244-220)÷40
=115×24÷40
=2760÷40
=69
=(185+15)×38
=200×38
=7600
478-145÷5×6
=478-29×6
=478-174
=304
50+129×28-42
=50+3612-42
=3662-42
=3620
1000-(560÷7+99)
=1000-(80+99)
=1000-179
=821
85×25×2×4
=85×2×(25×4)
=170×100
=17000
115×(244-220)÷40
=115×24÷40
=2760÷40
=69
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