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 2 of 11.
Syed said:
2 decades ago
Ya there is a short cut the concept is :
Let's look for the no. whose square ends with 1 from 1-10, we will find that there are only two such number that is 1 and 9. That is between 1-70 there will be 14 such number.
Now lets find the percentage. 14 is what percent of 70.
10% of 70 is 7
Therefore 20% of 70 will be 2 * 7 = 14 the answer is 20%.
Let's look for the no. whose square ends with 1 from 1-10, we will find that there are only two such number that is 1 and 9. That is between 1-70 there will be 14 such number.
Now lets find the percentage. 14 is what percent of 70.
10% of 70 is 7
Therefore 20% of 70 will be 2 * 7 = 14 the answer is 20%.
Sarika said:
9 years ago
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.
I.E.
100% -------> 70 number.
X --------> 14.
(100x14) / 70 = 20%.
Number of such number = 14.
I.E.
100% -------> 70 number.
X --------> 14.
(100x14) / 70 = 20%.
Sanjana said:
6 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?
Bradley S said:
1 year ago
@All.
Here, they have incorrectly missed the number range from 11-20, which includes 10 numbers (not 2). The ranges from 1-70, which include a 1 or 9. 11, 12, 13, 14, 15, 16, 17, 18, 19 = 10. All from 1 - 70 have 2. Therefore the total sum = 22/70 which equates to 31%.
Here, they have incorrectly missed the number range from 11-20, which includes 10 numbers (not 2). The ranges from 1-70, which include a 1 or 9. 11, 12, 13, 14, 15, 16, 17, 18, 19 = 10. All from 1 - 70 have 2. Therefore the total sum = 22/70 which equates to 31%.
(18)
Ravi kumar said:
1 decade ago
Hello friends here they asked just between numbers from 1 to 70 so we followed this procedure. It is not easy to find if they asked for larger numbers like 1 to 10000 like this. In this case can't keep go on counting so please tell a new shortcut method.
Ayas Kanta said:
8 years ago
Can anyone help me to solve this?
A seller got 5% commission on selling for Rs. 10000 and above he got 4% commission. One day he deposited Rs. 31100 in a company after deduction his commission then on that day what was the sale amount?
A seller got 5% commission on selling for Rs. 10000 and above he got 4% commission. One day he deposited Rs. 31100 in a company after deduction his commission then on that day what was the sale amount?
Shivam Tripathi said:
4 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)
Shahira said:
1 month ago
Numbers from 1 to 70.
1 unit digit -> 1,11,21,31,41,51,61 -> 7 numbers.
9 unit digit -> 9,19,29,39,49,59,69 -> 7 numbers.
So, the total 1 and 9 unit digits is 14 numbers.
Now percentage;
14/70 * 100 = 20%.
1 unit digit -> 1,11,21,31,41,51,61 -> 7 numbers.
9 unit digit -> 9,19,29,39,49,59,69 -> 7 numbers.
So, the total 1 and 9 unit digits is 14 numbers.
Now percentage;
14/70 * 100 = 20%.
(5)
Jeetendra Kushwaha said:
9 years ago
Please read the question carefully.
It says about that number which put in place of a unit and which must be 1 or 9.
So only these number are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.
So total 14 numbers.
It says about that number which put in place of a unit and which must be 1 or 9.
So only these number are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.
So total 14 numbers.
Basha said:
5 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)
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