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?
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:
96 comments Page 1 of 10.

Durai said:   1 month ago
!All.

Here, They asked 1 or 9, why all answers are included both 1 and 9, if we considered 1 or 9 only the percentage should be 10%.

Correct me, if I'm wrong.
(1)

Kaviarasan said:   2 months ago
@All.

Here is my explanation for the answer.

Let's take initial values as 100%, which means initially the fruit seller had some apples, so I take that as 100%.

Now, if he sells 40% of his apples, he has 60% of the apples remaining.

So, in the question, they have already stated that the seller has 420 apples after selling 40%.

Thus, we have:
60% = 420.
100% = x.

To solve this expression:
x = (420×100)60x = 60(420×100)​.
x = 700x = 700.

Therefore, the answer is 700.
(1)

Ankush kushwaha said:   3 months ago
1 to 9 = 2 digit (1,9) =2.
11 to 70 = [digit1-tens digit2-units].
At unit one place suppose I have put 1 there that means I have the choice to
put 6 digits at the tens place = 6 * 1 = 6.
similarily for 9 also = 6 *1 = 6.

The reason we are taking 6 digits is because it will exceed the range that is given.
So, total = 14,
14 = x /100 * 70,
x = 20%.

Manikeshwari said:   4 months ago
@Moses Ug.

We can't consider 12 to 18 because the question says in units place of a number it should either have 1 or 9 not in tens place.

Gokila said:   4 months ago
Why shouldn't we consider 10, 11, 12, 13, 14, 15, 16, 17, 18 as they have 1 in its unit?
(8)

Aruna said:   1 year ago
Numbers from 1 to 70.
Having 1 or 9 in unit digits,
1 seven times and 9 seven times,
14/70 * 100 = 20.
(16)

Moses Ug said:   1 year ago
Does 12 up to 18 have a digit 1 or not?

Anyone, please clarify.
(15)

Rasheed nasar said:   2 years ago
Very helpful explanation, Thanks. @Tabi.
(3)

Nikhil said:   2 years ago
@Lobsang.

Because, They didn't ask about us anyone's Square.

They just told you to find how many no belongs in 1to70 That last digit should come only 1 and 9. Like 01, 09, 11, 19, 21, 29. 69.

Hope you understood.
(19)

LOBSANG said:   2 years ago
Then why don't we consider 7 here because it also ends with 9 as a unit digit 7*7=49?

Anyone clarify it.
(1)


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