1+2=(1+2)×2/2=3的规律?

1+2=(1+2)×2/2=3的规律?
1+2= (1+2)×2/2=3
1+2+3=（1+3）×3/2=6
1+2+3+4=（1+4）×4/2=10
1+2+3+4+5=（1+5）×5/2=15
·······································
1+2+3+4+5+················n=（1+n）×n/2
（1）n个连续自然数之和的计算规律用语言叙述是：_________________________.
（2）计算1+2+3+4+··········+99+100
（3）求1+ 1/1+2 + 1/1+2+3 + 1/1+2+3+4 + 1/1+2+3+4+5 +···············+1/1+2+3+4+··········+100的值