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:
105 comments Page 3 of 11.
Shivam Tripathi said:
5 years ago
There are 10 digits from 0 to 9 total( 10 nos) out of which 1 and 9 are asked in question (2 digits) so in question at units place Bo's are not repeating.
Hence 2 digits out of 10 digits Make it 20%(2/10=20%).
Am I right?
Hence 2 digits out of 10 digits Make it 20%(2/10=20%).
Am I right?
(2)
Aditya Singh Shishodia said:
5 years ago
@All.
Unit place is the first digit and not the last. As per the place value system it would always begin from left to right. This is simply a wrongly phrased question.
Unit place is the first digit and not the last. As per the place value system it would always begin from left to right. This is simply a wrongly phrased question.
(2)
Villan said:
5 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 %.
Arushi said:
5 years ago
@Jim.
The unit digit is the ending digit.
The unit digit is the ending digit.
Durai Arasan T S said:
6 years ago
Why don't we consider the 12, 13, 18 because it has 1 as a unit digit?
(2)
Gnanikrishna said:
6 years ago
What is the unit's digit? Please explain me.
(2)
Basha said:
6 years ago
In every ten numbers, we have only two numbers that end with digits 1 or 9.
So b/w 1 to 70 we 14. (7*2 = 14).
Here 7 represents no of tens and 2 represents no of numbers that end with digit 1 or 9.
So, 14/70 * 100 = 20.
So b/w 1 to 70 we 14. (7*2 = 14).
Here 7 represents no of tens and 2 represents no of numbers that end with digit 1 or 9.
So, 14/70 * 100 = 20.
(2)
Jim said:
6 years ago
The question is not talking about ending with 1 or 9, but it's talking about numbers having 1 or 9.
Sanjana said:
7 years ago
@Shubham.
12^2 = 144 here, the last digit in 144 is four not "1" that's y 12 is not being taken.
Therefore, if the number with the last digit 1 and it's square the last digit is 1 is not being taken!
And it's the same with the other number like 13, 17.. and all!!
Got it?
12^2 = 144 here, the last digit in 144 is four not "1" that's y 12 is not being taken.
Therefore, if the number with the last digit 1 and it's square the last digit is 1 is not being taken!
And it's the same with the other number like 13, 17.. and all!!
Got it?
Shubham matekar said:
7 years ago
Why 12, 13... 17 has not considered? Please tell me.
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