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1. 口算。
0.75÷5 = 0.8×12.5 = 56 + 44 = 540÷90 = $\frac{2}{5}+\frac{1}{4}$ =
$\frac{3}{4}×\frac{8}{9}$ = 6.25×4 = 9.5-8.7 = 9.5 + 8.5 = 153÷3 =
0.75÷5 = 0.8×12.5 = 56 + 44 = 540÷90 = $\frac{2}{5}+\frac{1}{4}$ =
$\frac{3}{4}×\frac{8}{9}$ = 6.25×4 = 9.5-8.7 = 9.5 + 8.5 = 153÷3 =
答案
0.75÷5 = 0.15
0.8×12.5 = 10
56 + 44 = 100
540÷90 = 6
$\frac{2}{5}+\frac{1}{4}$ = $\frac{8}{20}+\frac{5}{20}$ = $\frac{13}{20}$
$\frac{3}{4}×\frac{8}{9}$ = $\frac{3×8}{4×9}$ = $\frac{2}{3}$
6.25×4 = 25
9.5-8.7 = 0.8
9.5 + 8.5 = 18
153÷3 = 51
0.8×12.5 = 10
56 + 44 = 100
540÷90 = 6
$\frac{2}{5}+\frac{1}{4}$ = $\frac{8}{20}+\frac{5}{20}$ = $\frac{13}{20}$
$\frac{3}{4}×\frac{8}{9}$ = $\frac{3×8}{4×9}$ = $\frac{2}{3}$
6.25×4 = 25
9.5-8.7 = 0.8
9.5 + 8.5 = 18
153÷3 = 51
2. 计算。
298 + 526= 48.12-20.89= 394×22= 715÷88=
5.12 + 0.93= 11-7.09= 305.9×68= 53.32÷0.62=
298 + 526= 48.12-20.89= 394×22= 715÷88=
5.12 + 0.93= 11-7.09= 305.9×68= 53.32÷0.62=
答案
298 + 526
= 300 - 2 + 526
= 826 - 2
= 822
48.12 - 20.89 = 27.23
394×22
= 394×(20+2)
= 394×20 + 394×2
= 7880 + 788
= 8668
715÷88 = 8.125
5.12 + 0.93 = 6.05
11 - 7.09
= 11.00 - 7.09
= 3.91
305.9×68
= 305.9×(60+8)
= 305.9×60 + 305.9×8
= 18354 + 2447.2
= 20801.2
53.32÷0.62
= (53.32×100)÷(0.62×100)
= 5332÷62
= 86
= 300 - 2 + 526
= 826 - 2
= 822
48.12 - 20.89 = 27.23
394×22
= 394×(20+2)
= 394×20 + 394×2
= 7880 + 788
= 8668
715÷88 = 8.125
5.12 + 0.93 = 6.05
11 - 7.09
= 11.00 - 7.09
= 3.91
305.9×68
= 305.9×(60+8)
= 305.9×60 + 305.9×8
= 18354 + 2447.2
= 20801.2
53.32÷0.62
= (53.32×100)÷(0.62×100)
= 5332÷62
= 86
(1)根据$28×37=1036$,直接写出下面各题的得数。
$28×3.7=$
$1.036÷28=$
$0.28×3.7=$
$1036÷2.8=$
$28×0.037=$
$103.6÷28=$
$28×3.7=$
$1.036÷28=$
$0.28×3.7=$
$1036÷2.8=$
$28×0.037=$
$103.6÷28=$
答案
$28×3.7=103.6$
$1.036÷28=0.037$
$0.28×3.7=1.036$
$1036÷2.8=370$
$28×0.037=1.036$
$103.6÷28=3.7$
$1.036÷28=0.037$
$0.28×3.7=1.036$
$1036÷2.8=370$
$28×0.037=1.036$
$103.6÷28=3.7$
(2)在〇里填“＞”“＜”或“=”。
$\frac{4}{7}×\frac{8}{9} ◯ \frac{4}{7}$
$\frac{4}{7}÷\frac{8}{9} ◯ \frac{4}{7}$
$38×1.05 ◯ 38$
$68÷0.98 ◯ 68$
$7.9×0.98 ◯ 7.9$
$43÷1.1 ◯ 43$
$\frac{4}{7}×\frac{8}{9} ◯ \frac{4}{7}$
$\frac{4}{7}÷\frac{8}{9} ◯ \frac{4}{7}$
$38×1.05 ◯ 38$
$68÷0.98 ◯ 68$
$7.9×0.98 ◯ 7.9$
$43÷1.1 ◯ 43$
答案
$\frac{4}{7}×\frac{8}{9} ＜ \frac{4}{7}$
$\frac{4}{7}÷\frac{8}{9} ＞ \frac{4}{7}$
$38×1.05 ＞ 38$
$68÷0.98 ＞ 68$
$7.9×0.98 ＜ 7.9$
$43÷1.1 ＜ 43$
$\frac{4}{7}÷\frac{8}{9} ＞ \frac{4}{7}$
$38×1.05 ＞ 38$
$68÷0.98 ＞ 68$
$7.9×0.98 ＜ 7.9$
$43÷1.1 ＜ 43$
(3)分母是9的所有真分数的和是()。
答案
$\frac{1}{9} + \frac{2}{9} + \frac{3}{9} + \frac{4}{9} + \frac{5}{9} + \frac{6}{9} + \frac{7}{9} + \frac{8}{9}$
$=(\frac{1}{9}+\frac{8}{9})+(\frac{2}{9}+\frac{7}{9})+(\frac{3}{9}+\frac{6}{9})+(\frac{4}{9}+\frac{5}{9})$
$=1+1+1+1$
$=4$
答：4。
$=(\frac{1}{9}+\frac{8}{9})+(\frac{2}{9}+\frac{7}{9})+(\frac{3}{9}+\frac{6}{9})+(\frac{4}{9}+\frac{5}{9})$
$=1+1+1+1$
$=4$
答：4。
(4)9.07560756…里,小数点后第115位的数是()。
答案
115÷4=28……3
答：小数点后第115位的数是5。
答：小数点后第115位的数是5。
(5)在“()÷8=16……()”中,被除数最大是()。
答案
余数最大为：8-1=7
被除数：16×8+7=128+7=135
答：被除数最大是135。
被除数：16×8+7=128+7=135
答：被除数最大是135。
(6)从28.8中连续减()个3.6,得数为0。
答案
28.8÷3.6=8
答：8。
答：8。
4. 计算下面各题。
$1.99+5.03$
$9.72÷0.36$
$900-17.5$
$9.46×2.7$
$\frac{4}{7}÷\frac{4}{7}$
$\frac{4}{7}+\frac{4}{7}$
$1.99+5.03$
$9.72÷0.36$
$900-17.5$
$9.46×2.7$
$\frac{4}{7}÷\frac{4}{7}$
$\frac{4}{7}+\frac{4}{7}$
答案
1.99+5.03=7.02
9.72÷0.36=(9.72×100)÷(0.36×100)=972÷36=27
900-17.5=882.5
9.46×2.7=25.542
$\frac{4}{7}÷\frac{4}{7}=\frac{4}{7}×\frac{7}{4}=1$
$\frac{4}{7}+\frac{4}{7}=\frac{4+4}{7}=\frac{8}{7}$
9.72÷0.36=(9.72×100)÷(0.36×100)=972÷36=27
900-17.5=882.5
9.46×2.7=25.542
$\frac{4}{7}÷\frac{4}{7}=\frac{4}{7}×\frac{7}{4}=1$
$\frac{4}{7}+\frac{4}{7}=\frac{4+4}{7}=\frac{8}{7}$
