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.
Subash said:
7 years ago
Thank you @Manisha.
Shaunak said:
8 years ago
How did we get?
Daniel said:
8 years ago
Hey, 10, 11, 12, 13, 14, 15, 16, 17, 18 not count?
It have component number 1 too.
It have component number 1 too.
Aditys said:
8 years ago
The question should be 1 and 9 not 1 or 9.
Faraz said:
8 years ago
It is very simple.
Now there are 14 numbers which start from 1 or 9 It means 14 out of 70.
Now take percentage of 14 out of 70 means multiply by 100 which is equal to 20%.
Now there are 14 numbers which start from 1 or 9 It means 14 out of 70.
Now take percentage of 14 out of 70 means multiply by 100 which is equal to 20%.
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)?
Abba said:
8 years ago
What about 11, 12, 13, 14, 15, 16, 17, and 18?
Udit said:
8 years ago
Why 7 not included? It ends with 9 after squaring.
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.
Vamshi sai said:
8 years ago
I didn't get question properly can anyone help me to get it.
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