[問題]天山 03-26

[Janet]

Q26:
In the decimal representation of x, where 0 < x < 1, is the tenths digit if x nonzero?
(1) 16x is an integer.
(2) 8x is an integer.

ans:B

請問解題思路?

[enim]

Q26:
In the decimal representation of x, where 0 < x < 1, is the tenths digit if x nonzero?
(1) 16x is an integer.
(2) 8x is an integer.

ans:B

請問解題思路?

題目:問十分位數是否為非零？

條件一
16x為整數
代表x最小必大於0.0625（拿1去除16）
此時，x的十分位數可能為0，但也可能不為0

條件二
8x為整數
代表x最小必大於0.125（同理）
故x的十分位數必為非0

得證

有錯請指正

[Janet]

謝謝~說得非常清楚~~

[rockermichael]

but，0.126*8=1.008，tenths digit is zero. I am confused~~~

[rockermichael]

Ok! never mind this artical. I misunderstood the question. Sorry~~~