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Aptitude - Percentage - Discussion

Discussion Forum : Percentage - General Questions (Q.No. 4)
Percentage
4.
What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?
1
14
20
21
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 8 of 11.
Elly said:   9 years ago
@All.

This question has been tricky to understand but thanks to the various explanations. I've got it.
Kamall Barik said:   9 years ago
Thanks for your shortcut @Syed.
Ramesh kannan said:   8 years ago
Very easy 100 ÷ 0 = 1.4285714286.
Next 1.4285714286 * 14 = 20.
Panda said:   8 years ago
Why 1s of 12, 13,14...,18 is not calculated? Please explain.
Mustafa said:   8 years ago
Why 12, 13, 14, 15, 16, 17, 18 are not included?
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?
Manisha said:   8 years ago
What percentage of numbers from 1 to 90 has a 1 or 9 as one of the digits?

Can anyone solve this?
Vamshi sai said:   8 years ago
I didn't get question properly can anyone help me to get it.
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.
Udit said:   8 years ago
Why 7 not included? It ends with 9 after squaring.
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