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 4 of 11.
Aditya Singh Shishodia said:
4 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)
Durai said:
1 year ago
!All.
Here, They asked 1 or 9, why all answers are included both 1 and 9, if we considered 1 or 9 only the percentage should be 10%.
Correct me, if I'm wrong.
Here, They asked 1 or 9, why all answers are included both 1 and 9, if we considered 1 or 9 only the percentage should be 10%.
Correct me, if I'm wrong.
(13)
Manikeshwari said:
1 year ago
@Moses Ug.
We can't consider 12 to 18 because the question says in units place of a number it should either have 1 or 9 not in tens place.
We can't consider 12 to 18 because the question says in units place of a number it should either have 1 or 9 not in tens place.
(2)
Anonymous said:
1 year ago
@All.
Here, In 1s digit there are 14 numbers with 1 and 9.
So 70% = 100.
14% = x.
Cross multiply.
70 (x) =14 (100).
X = 1400/70.
X = 20.
Here, In 1s digit there are 14 numbers with 1 and 9.
So 70% = 100.
14% = x.
Cross multiply.
70 (x) =14 (100).
X = 1400/70.
X = 20.
(5)
Cavendish said:
8 years ago
It has nothing to do with the squares.
Just count the numbers ending with 1 or 9 in between 1 and 70 (inclusively). That's all.
Just count the numbers ending with 1 or 9 in between 1 and 70 (inclusively). That's all.
Abhishek said:
7 years ago
@All.
If we increase the parameter from 70 to 100 then what?
I mean if we count from 1 to 100 than what will be the solution?
If we increase the parameter from 70 to 100 then what?
I mean if we count from 1 to 100 than what will be the solution?
Soujanya said:
9 years ago
What if larger numbers are given?
Eg: 1 to 10000. We cannot count manually all the numbers right, Is there any shortcut?
Eg: 1 to 10000. We cannot count manually all the numbers right, Is there any shortcut?
Renukanth said:
8 years ago
What is the need for squaring here, they just asked to find out how man number are there, with the unit digit (1 and 9)?
Sanjana said:
7 years ago
Digits with 1 in unitary place:7.
Digits with 9 in unitary place:7.
7+7=14,
The total numbers=70.
14/70*100=140/7=20%.
Digits with 9 in unitary place:7.
7+7=14,
The total numbers=70.
14/70*100=140/7=20%.
(1)
Avnish said:
1 decade ago
In every 10 digits there is 1 or 9 are coming,
So we can tell that what is the % of 2 out of 10,
That is 20 % only.
So we can tell that what is the % of 2 out of 10,
That is 20 % only.
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