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:
103 comments Page 7 of 11.
Gain.... said:
9 years ago
But they asking 1 or 9 (if they asking instead of this 1 and 9). What will be the answer?
Gokila said:
2 years ago
Why shouldn't we consider 10, 11, 12, 13, 14, 15, 16, 17, 18 as they have 1 in its unit?
(16)
Uday said:
9 years ago
We cannot keep 2 digits at a time at a unit place, right. so there should be 1 or 9.
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.
Amit Das said:
9 years ago
Why not 12, 13, 14, . , 18? All have 1 in them! It is told 1 OR 9. Not 1 AND 9?
Smithy said:
9 years ago
How to find those 14 numbers in between 1-70 is there any shortcut to find it?
Rekha said:
7 years ago
13^2 is 169, so it ends with 9. But why 13 should not be considered b/w them?
Durai Arasan T S said:
5 years ago
Why don't we consider the 12, 13, 18 because it has 1 as a unit digit?
(2)
Phani said:
1 decade ago
Hello friends! in the question, not mentioned that the word "square".
Ramesh kannan said:
9 years ago
Very easy 100 ÷ 0 = 1.4285714286.
Next 1.4285714286 * 14 = 20.
Next 1.4285714286 * 14 = 20.
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