计算:(1/2+1/4+1/6+1/8)−(1/3+1/6+1/9+1/12)+(1/4+1/8+1/12+1/16)−(1/5+1/10+1/15+1/20)=_.

问题描述:

计算:(

1
2
+
1
4
+
1
6
+
1
8
)−(
1
3
+
1
6
+
1
9
+
1
12
)+(
1
4
+
1
8
+
1
12
+
1
16
)−(
1
5
+
1
10
+
1
15
+
1
20
)=______.

(12+24+18+116)-(13+16+19+112)+(14+18+112+116)+(15+110+115+120)=12×(1+12+13+14)−13×(1+12+13+14)+14×(1+12+13+14)−15×(1+12+13+14),=(1+12+13+14)×(12−13+14−15),=2512×1360,=65144....