6+12+18+24+30+36+42+48+54+60+66+72+78+84+90+96+102······+600000000等于多少?

问题描述:

6+12+18+24+30+36+42+48+54+60+66+72+78+84+90+96+102······+600000000等于多少?

这样
6+12+18+24+30+36+42+48+54+60+66+72+78+84+90+96+102······+600000000
=[(6+600000000)*600000000/6]/2=300000000300000000

等差数列~首项加末项乘以项数除以2~-~

(6+600000000)×(600000000/6)/2
=600000006×100000000/2
=60000000600000000/2
=30000000300000000

6+12+18+24+30+36+42+48+54+60+66+72+78+84+90+96+102······+600000000
=[(6+600000000)*600000000/6]/2=300000000300000000