P5 Maths question

[匿名]

2010-11-08 7:23 am

A box of pencil, if it divides into 8 ppl..it remains 6; if divides into 6ppl, it remains 4; if it divides into 4ppl, it remain 2 pencil. What is the min number of the pencill?

更新1:

We know the solution is : firstly, find the LCM of the ppl, then mins 2, but how do we know that we need to mins "2"?

回答 (1)

用戶2053

2010-11-08 8:50 am

✔ 最佳答案

Let x be the min number of the pencil.
Now add 2 more pencil to the box.Then divides into 8 ppl..it remains 6 + 2 = 8 now ,
therefore x+2 is a multiple of 8 .if divides into 6ppl, it remains 4 + 2 = 6 ,
therefore x+2 is a multiple of 6 ,if it divides into 4ppl, it remain 2 + 2 = 4 ,
therefore x+2 is a multiple of 4.x+2 is the LCM of 4 , 6 and 8 ,x+2 = 24x = 22
The min number of the pencill is 22.

2010-11-08 12:12:48 補充：
Observe that 8 - 6 = 6 - 4 = 4 - 2 = 2.

So we need to mins "2".

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