一題數學題目
回答 (4)
2015-02-12 5:11 am
✔ 最佳答案
1~100中，4和6的倍數不算，剩下的數的總和是多少? Sol
N(4)=4+8+12+…+100=4*(1+2+3+…+25)=4*(1+25)*25/2=1300
N(6)=6+12+18+…+96=6*(1+2+3+…+16)=6*(1+16)*16/2=816
[4，6]=12
N(12)=12+24+36+…+96=12*(1+2+3+…+8)=12*(1+8)*8/2=432
1+2+3+…+100=(1+100)*100/2=5050
5050-(1300+816－432)=3366
2015-02-12 6:19 am
螞蟻知識長正解~~~
2015-02-12 5:32 am
100/4=25
25/2=12...1
(100+4)*12+13*4
=1300
100/6=16...,4
(100-4+6)*16/2
=816
100/12=8....4
(12+100-4)*8/2
=432
1300+816-432+6
=1690
(1+100)*100/2
=5050
5050-1690
=3361
25/2=12...1
(100+4)*12+13*4
=1300
100/6=16...,4
(100-4+6)*16/2
=816
100/12=8....4
(12+100-4)*8/2
=432
1300+816-432+6
=1690
(1+100)*100/2
=5050
5050-1690
=3361
2015-02-12 5:09 am
100(1+100)/2-25(4+100)/2-16(96+6)/2=2934
收錄日期: 2021-04-24 23:25:20
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20150211000010KK04098