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 9 of 11.
Kiran shahzadi said:
1 decade ago
What is mean by unit digit?
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?
Raju said:
1 decade ago
25% of a number is less than 18% of 650 by 19. Then the number is?
Please send me the solution.
Please send me the solution.
Siddharth said:
1 decade ago
Here's how it is done:
From 1 to 10---only 2 numbers have 1 & 9 at unit's place i.e.= 1 &9.
Therefore, from 10 to 20---11 and 19 have 1 & 9 at unit's place.
Then from 20 to 30---21, 29.
From 30 to 40---31, 39
From 60 to 70---61, 69.
So what concluded here is that each set has 2 numbers which have
1,9 at unit's place.
Therefore: 7 sets=2*7=total 14 numbers.
From 1 to 10---only 2 numbers have 1 & 9 at unit's place i.e.= 1 &9.
Therefore, from 10 to 20---11 and 19 have 1 & 9 at unit's place.
Then from 20 to 30---21, 29.
From 30 to 40---31, 39
From 60 to 70---61, 69.
So what concluded here is that each set has 2 numbers which have
1,9 at unit's place.
Therefore: 7 sets=2*7=total 14 numbers.
Meena said:
1 decade ago
As per the given we should count only the digits which end with either 1 or 9(i.e, units place).
Suppose if we consider a no 527.
7 is in units place.
2 in tens place and.
5 is in Hundred's place.
In the same we get 1,9,11,19,21,29....so on 14 digits for the above question.
To be simple:
We have no's end with 1 = 7.
We have no's end with 9 = 7.
So total = 14.
Ans: 14/70*100 = 20%.
Suppose if we consider a no 527.
7 is in units place.
2 in tens place and.
5 is in Hundred's place.
In the same we get 1,9,11,19,21,29....so on 14 digits for the above question.
To be simple:
We have no's end with 1 = 7.
We have no's end with 9 = 7.
So total = 14.
Ans: 14/70*100 = 20%.
Zaman said:
1 decade ago
We should first understand the question ?
The question asks the numbers with 1 or 9 in the unit digit that is in the last digit or ending with 1 or 9.
12, 13, 14 have 2, 3 and 4 in the unit digit respectively.
The question asks the numbers with 1 or 9 in the unit digit that is in the last digit or ending with 1 or 9.
12, 13, 14 have 2, 3 and 4 in the unit digit respectively.
Niraj said:
1 decade ago
What about 12,13,14,15,16,17,18?
RAVI TEJA ADARI said:
1 decade ago
Why should take ends with '1'?
Why not take other numbers?
Why not take other numbers?
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.
Daniel said:
1 decade ago
The question doesn't specify that the digits 1 or 9 must be the last digits, so clearly all the number in the teens, would qualitfy as nubers between 1 and 70 that have the digit 1 OR 9.
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