4+8+12+16+20+ +400要简便还有过程谢谢!

4+8+12+16+20+ +400要简便还有过程谢谢!
4+8+12+16+20+ +400要简便还有过程谢谢!

4+8+12+16+20+ +400要简便还有过程谢谢!
4+8+12+16+20+400
=（4+16）+（8+12）+（20+400）
=20+20+420
=460

（4+100）*50=5200

20200. 1+2+3+..+100的4倍=5050*4=20200

4+8+12+16+20+400=(4+16)+(8+12)+20+400=20+20+20+400=460

4*1+4*2+4*3.....+4*100=4*(1+100)=4*5050=20200

4*(1+2+3+ +100)=4*5050=20200

4+8+12+16+20+ +400
=(4+400)*100/2
=404*50
=20200