Interview Math Challenge: How Do You Calculate 35% of 90 on the Spot?

Please guide me, what is 35% of 90? I was asked this question during my interview, and I was blank. 

In my opinion, it's a simple question to check your aptitude. The answer is 31.5.

Regards,
Manish

Cool dude... Always, whatever percentage is asked, divide it by 10. This will give you 10%. Proceed from there, and it will be easy.

35% of 90 is nothing but 35/100*90 = 31.5. This is an aptitude question, a simple question often posed by interviewers.

Simple Math Question

A simple school-level math question. It's not really a question to test your aptitude.

Probably an easy question to lead you towards tougher questions or to test your response time, alertness, presence of mind, or to judge if you are nervous or tense.

I have corrected the spelling errors, improved the punctuation, and adjusted the formatting to ensure clarity and readability. Let me know if you need any further assistance.

Regards

Are you really serious about checking this with us and telling us that you couldn't answer this in the interview? Come on, man, this is standard 3rd level Math. As easily calculated by TwoHearts, it is 35/100 * 90 = 31.5. So, I'm not sure where or why you got stuck.

Anyways, I hope you got the job despite this inability.

Thanks,
Kanishka

Dear Feb, this is called practical mathematics. In Hindi medium schools, teachers teach how to solve mathematics questions using a method called fraction solving. My grandfather is 86 years old, and he can calculate any mathematics question even before any of us geniuses could pick up the calculators from our tables.

Practical Mathematics Calculation

The best system would have been to divide 90 by 10 = 9; this is 10 percent. Now, for thirty percent, multiply 9 by 3 = 27. Next, add half of 9, which is 4.5, to 27, resulting in 31.5 as the answer. Believe me, if you practice this, you will be faster than most people.

Purpose of Posting a Query

The purpose of posting a query and discussion here is not to ridicule the poster or to teach them how percentages are calculated. They obviously know it, and HR professionals are not expected to teach it, nor should they take pride in knowing basic math.

Real Purpose of the Post

The real purpose of the post is to understand why such questions are asked in interviews. How do such questions help or not help in selecting the right candidates? Will such questions have an impact on the selection and rejection of candidates?

Simple Calculation

35% of 90 is calculated as follows: 35 * 90 / 100 = 31.5

75% of 75 is calculated as follows: 75 * 75 / 100 = 56.25

Regards

Well said, friend. I also thought the same while reading the replies. We are too harsh on our fellow members! Thanks for this simple and wonderful, thought-worthy post!

Regards

It's such a simple question to answer. I don't understand why you were blank at that time. 樂

35/100 * 90 = 31.5

Hi Ravi, thanks for sharing such an interesting trick for calculating squares of digits ending with five. It can be useful while taking aptitude or entrance tests. Could you please share some more tricks for mathematical aptitude questions to get quicker answers?

Thanks,
Rashee

Hi all, whenever a question is asked, some members reply in a sarcastic way, which may hurt the feelings of the person who posed the question. For example, K. Ravi says, "Hey, go back to school!" These kinds of replies could be avoided. Mr. Ravi must know that not everyone is as intelligent as him. If possible, one should help; otherwise, keep quiet. It doesn't look nice to decry somebody. I do hope that Mr. Ravi will take this in a positive way. Let us all be model HR people for others to follow.

Regards,
M.J. Subramanyam, Bangalore

Thank you for all the replies. The crux and the gist that I gather from all replies and posts of this particular series is that there is an easier and faster method of calculating numbers. Can anybody tell me if there's any good book on Vedic Math available, online or offline?

Thanks,
Kanishka