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