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:
107 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:
10 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%.
Anand said:
2 weeks ago
To find the percentage of numbers from 1 to 70.
Let's say 1-70 = 100%.
So in there, we want the percentage of 1 and 9 numbers, so we just have to do.
Every 1-70 has 1, and every 1-70 has 9.
So if 1-70 = 100%, 1 is 10% and 9 is 10%, and we sum the percentages, we get 10+10 = 20% answer.
Let's say 1-70 = 100%.
So in there, we want the percentage of 1 and 9 numbers, so we just have to do.
Every 1-70 has 1, and every 1-70 has 9.
So if 1-70 = 100%, 1 is 10% and 9 is 10%, and we sum the percentages, we get 10+10 = 20% answer.
Sanjana said:
7 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:
2 years 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%.
(23)
Kannan said:
1 month ago
The number between 1 and 70 should contain 1 or 9 in the unit digits, meaning
The numbers are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.
Total number of 1 or 9 in the unit digits = 14
Then,
They are asking percent so,
14/70 * 100 = 2 * 10 = 20%.
The numbers are 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.
Total number of 1 or 9 in the unit digits = 14
Then,
They are asking percent so,
14/70 * 100 = 2 * 10 = 20%.
(2)
Creti said:
6 months ago
It's Very Easy:
Here, the numbers from 1 to 70 have 1 or 9.
In the units digit?
So, we have 1 to 70.
1 or 9 - here 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.
Here, 14 are there;
14/70 × 100.
14/7 × 10.
(140/7) = 20.
Here, the answer is 20
Here, the numbers from 1 to 70 have 1 or 9.
In the units digit?
So, we have 1 to 70.
1 or 9 - here 1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69.
Here, 14 are there;
14/70 × 100.
14/7 × 10.
(140/7) = 20.
Here, the answer is 20
(9)
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:
9 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:
5 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)
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