Question

1/20+1/6+1/12+1/20+1/30等于多少

Answer 1

分数 1/20+1/6+1/12+1/20+1/30 = 23/60
寻找他们的最小公倍数，既：1/20=3/60,1/6=10/60,1/12=5/60,1/20=3/60,1/30=2/60;
分母不变，分子相加，既：3/60+10/60+5/60+3/60+2/60=23/60

Answer 2

1/6+1/12+1/20+1/30
= 1/(2×3)+1/(3×4)+1/(4×5)+1/(5×6)
= 1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6
= 1/2-1/6
= 1/3

1/20+1/6+1/12+1/20+1/30
= 1/20+（1/6+1/12+1/20+1/30）
= 1/20 + 1/3
= 3/60+20/60
= 23/60

Answer 3

。

Answer 4

原式＝3/60+10/60+5/60+3/60+2/60
=23/60