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Several junior high school calculation problems -1 / 10 by 11 - 1 / 11 by 12 - 1 / 12 by 13. - 1 / 19 by 20 -1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/42
-1 / 10 by 11 - 1 / 11 by 12 - 1 / 12 by 13. - 1 / 19 by 20 = - (1 / 10-1 / 11 + 1 / 11-1 / 12 +. + 1 / 19-1 / 20) = - (1 / 10-1 / 20) = - 1 / 2-1 / 2 - 1 / 6 - 1 / 12 - 1 / 20 - 1 / 30 - 1 / 42 = - (1-1 / 2 + 1 / 2-1 / 3 + 1 / 3-1 / 4 +... + 1 / 6-1 / 7) = - (1-1 / 7) = - 6 / 7
Several calculation problems in junior high school~
(-1000)x(3/10-1/2+1/5-0.1)=
(-.359)x(-4/7)-2.14x(-4/7)+6x(14/7)=
19 13/14x(-14)=
(1/50-1)(1/49-1)(1/24-1)...(1/4-1)(1/3-1)(1/2-1)=
100
thirteen point four two eight
The third question is Shenma
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