Aptitude - Percentage - Discussion
Discussion Forum : Percentage - General Questions (Q.No. 4)
4.
What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?
Answer: Option
Explanation:
Clearly, the numbers which have 1 or 9 in the unit's digit, have squares that end in the digit 1. Such numbers from 1 to 70 are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.
Number of such number =14
 Required percentage = |
 |
14 | x 100 |  % = 20%. |
| 70 |
Video Explanation: https://youtu.be/cBamI6iRNIA
Discussion:
102 comments Page 5 of 11.
Gopal said:
1 decade ago
@pankaj.
It is wrong method unit digit means endshould be 1 or 9.
And 10 will be end in 0 so 10 is not include.
It is wrong method unit digit means endshould be 1 or 9.
And 10 will be end in 0 so 10 is not include.
Shivaranjitha said:
9 years ago
Y is less than 117 by 19, means; Either y =117 - 19 or 117 - y = 19.
I'm confused with this. Please answer this.
I'm confused with this. Please answer this.
Hanu said:
1 decade ago
They given unit digit is 1 or 9.
Suppose take 13 it is 169 so here unit digit is 9 so why it is not correct?
Suppose take 13 it is 169 so here unit digit is 9 so why it is not correct?
Joape said:
1 decade ago
It does not count 10, 12, 13, 14, 15, 16, 17, 18.
and they did not state about the square in the question.
and they did not state about the square in the question.
LOBSANG said:
3 years ago
Then why don't we consider 7 here because it also ends with 9 as a unit digit 7*7=49?
Anyone clarify it.
Anyone clarify it.
(1)
Elly said:
9 years ago
@All.
This question has been tricky to understand but thanks to the various explanations. I've got it.
This question has been tricky to understand but thanks to the various explanations. I've got it.
Yashwitha said:
9 years ago
Then what about the numbers of 11, 12, 113, 14, 15, 19 even 1 is their, then why it is not considered?
Aruna said:
2 years ago
Numbers from 1 to 70.
Having 1 or 9 in unit digits,
1 seven times and 9 seven times,
14/70 * 100 = 20.
Having 1 or 9 in unit digits,
1 seven times and 9 seven times,
14/70 * 100 = 20.
(17)
Villan said:
4 years ago
The simplest method is by counting the unit places as 3 and 7.
So, there are 14 nos.
14/70*100=20 %.
So, there are 14 nos.
14/70*100=20 %.
Ross said:
1 decade ago
I see that number 10 is not included into consideration even though it has 1 in its digit unit, why?
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