1. 直接写出得数。
$8.5 + 10.5 =$ $56×0.7 =$ $5 - \frac{3}{10} =$
$25÷(\frac{2}{10} + \frac{3}{10}) =$ $29.05 - 6.75 =$ $\frac{1}{4}×2 + 6×\frac{1}{4} =$
$100 - 99.9 =$ $1÷\frac{13}{14} =$ $9.27×0.2 =$
$(1 - \frac{2}{9})÷14 =$ $0 + 9.9 + 0.1 =$ $98.2 + 5 + 1.8 =$
$8.5 + 10.5 =$ $56×0.7 =$ $5 - \frac{3}{10} =$
$25÷(\frac{2}{10} + \frac{3}{10}) =$ $29.05 - 6.75 =$ $\frac{1}{4}×2 + 6×\frac{1}{4} =$
$100 - 99.9 =$ $1÷\frac{13}{14} =$ $9.27×0.2 =$
$(1 - \frac{2}{9})÷14 =$ $0 + 9.9 + 0.1 =$ $98.2 + 5 + 1.8 =$
答案
$8.5 + 10.5 = 19$
$56×0.7 = 39.2$
$5 - \frac{3}{10} = 4.7$
$25÷(\frac{2}{10} + \frac{3}{10}) = 25÷\frac{1}{2} = 50$
$29.05 - 6.75 = 22.3$
$\frac{1}{4}×2 + 6×\frac{1}{4} = \frac{1}{4}×(2+6) = 2$
$100 - 99.9 = 0.1$
$1÷\frac{13}{14} = \frac{14}{13}$
$9.27×0.2 = 1.854$
$(1 - \frac{2}{9})÷14 = \frac{7}{9}×\frac{1}{14} = \frac{1}{18}$
$0 + 9.9 + 0.1 = 10$
$98.2 + 5 + 1.8 = (98.2+1.8)+5 = 105$
$56×0.7 = 39.2$
$5 - \frac{3}{10} = 4.7$
$25÷(\frac{2}{10} + \frac{3}{10}) = 25÷\frac{1}{2} = 50$
$29.05 - 6.75 = 22.3$
$\frac{1}{4}×2 + 6×\frac{1}{4} = \frac{1}{4}×(2+6) = 2$
$100 - 99.9 = 0.1$
$1÷\frac{13}{14} = \frac{14}{13}$
$9.27×0.2 = 1.854$
$(1 - \frac{2}{9})÷14 = \frac{7}{9}×\frac{1}{14} = \frac{1}{18}$
$0 + 9.9 + 0.1 = 10$
$98.2 + 5 + 1.8 = (98.2+1.8)+5 = 105$
2. 脱式计算。(能简算的要简算)
$(48 + 24)÷(171÷19)$ $(\frac{5}{4} + 0.75)÷\frac{11}{8}×11$
$90 - (15 + 35×\frac{5}{7})$ $\frac{1}{6}×[(\frac{1}{14} + \frac{3}{7})÷\frac{7}{9} - \frac{1}{2}]$
$(48 + 24)÷(171÷19)$ $(\frac{5}{4} + 0.75)÷\frac{11}{8}×11$
$90 - (15 + 35×\frac{5}{7})$ $\frac{1}{6}×[(\frac{1}{14} + \frac{3}{7})÷\frac{7}{9} - \frac{1}{2}]$
答案
(48 + 24)÷(171÷19)
=72÷9
=8
$(\frac{5}{4} + 0.75)÷\frac{11}{8}×11$
=$(\frac{5}{4} + \frac{3}{4})×\frac{8}{11}×11$
=2×$(\frac{8}{11}×11)$
=2×8
=16
90 - (15 + 35×$\frac{5}{7}$)
=90 - (15 + 25)
=90 - 40
=50
$\frac{1}{6}×[(\frac{1}{14} + \frac{3}{7})÷\frac{7}{9} - \frac{1}{2}]$
=$\frac{1}{6}×[(\frac{1}{14} + \frac{6}{14})×\frac{9}{7} - \frac{1}{2}]$
=$\frac{1}{6}×[\frac{1}{2}×\frac{9}{7} - \frac{1}{2}]$
=$\frac{1}{6}×[\frac{9}{14} - \frac{7}{14}]$
=$\frac{1}{6}×\frac{1}{7}$
=$\frac{1}{42}$
=72÷9
=8
$(\frac{5}{4} + 0.75)÷\frac{11}{8}×11$
=$(\frac{5}{4} + \frac{3}{4})×\frac{8}{11}×11$
=2×$(\frac{8}{11}×11)$
=2×8
=16
90 - (15 + 35×$\frac{5}{7}$)
=90 - (15 + 25)
=90 - 40
=50
$\frac{1}{6}×[(\frac{1}{14} + \frac{3}{7})÷\frac{7}{9} - \frac{1}{2}]$
=$\frac{1}{6}×[(\frac{1}{14} + \frac{6}{14})×\frac{9}{7} - \frac{1}{2}]$
=$\frac{1}{6}×[\frac{1}{2}×\frac{9}{7} - \frac{1}{2}]$
=$\frac{1}{6}×[\frac{9}{14} - \frac{7}{14}]$
=$\frac{1}{6}×\frac{1}{7}$
=$\frac{1}{42}$
3. 解决问题。
某电视机厂要印制产品宣传资料。甲印刷厂提出:每份材料收$1$元印制费,另收$1500$元制版费。乙印刷厂提出:每份材料收$2.5$元印制费,不收制版费。
(1)印制$800$份宣传材料,选哪家印刷厂比较合算?
(2)电视机厂拟拿出$3000$元用于印制宣传资料,找哪家印刷厂比较合算?
(3)印制多少份时,两家印刷厂收费相同?
某电视机厂要印制产品宣传资料。甲印刷厂提出:每份材料收$1$元印制费,另收$1500$元制版费。乙印刷厂提出:每份材料收$2.5$元印制费,不收制版费。
(1)印制$800$份宣传材料,选哪家印刷厂比较合算?
(2)电视机厂拟拿出$3000$元用于印制宣传资料,找哪家印刷厂比较合算?
(3)印制多少份时,两家印刷厂收费相同?
答案
(1)
甲印刷厂:$1×800 + 1500 = 2300$(元)
乙印刷厂:$2.5×800 = 2000$(元)
$2000 < 2300$
答:选乙印刷厂比较合算。
(2)
甲印刷厂可印制份数:$(3000 - 1500)÷1 = 1500$(份)
乙印刷厂可印制份数:$3000÷2.5 = 1200$(份)
$1500 > 1200$
答:选甲印刷厂比较合算。
(3)
解:设印制$x$份时,两家印刷厂收费相同。
$x + 1500 = 2.5x$
$2.5x - x = 1500$
$1.5x = 1500$
$x = 1000$
答:印制1000份时,两家印刷厂收费相同。
甲印刷厂:$1×800 + 1500 = 2300$(元)
乙印刷厂:$2.5×800 = 2000$(元)
$2000 < 2300$
答:选乙印刷厂比较合算。
(2)
甲印刷厂可印制份数:$(3000 - 1500)÷1 = 1500$(份)
乙印刷厂可印制份数:$3000÷2.5 = 1200$(份)
$1500 > 1200$
答:选甲印刷厂比较合算。
(3)
解:设印制$x$份时,两家印刷厂收费相同。
$x + 1500 = 2.5x$
$2.5x - x = 1500$
$1.5x = 1500$
$x = 1000$
答:印制1000份时,两家印刷厂收费相同。
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