Best way to convert large fractions to decimals

mental math
New answer on Dec 01, 2019
5 Answers
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Anonymous A asked on Nov 16, 2019

E.g. I got stuck on how to do 11/275 during a case

What is the best trick for something like this and many others

Are there any recourses to practice large fractions?

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Antonello
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replied on Nov 16, 2019
McKinsey | MBA professor for consulting interviews

Hi,
here you can find a detailed approach to solve it in a quick approximated way and in an accurate way: https://www.youtube.com/watch?v=do_IbHId2Os

I recommend you to take a look at the channel, I really appreciate their video on fast math.

Best,
Anto

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Deniz
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replied on Nov 17, 2019
BCG | A.T. Kearney | University of Cambridge | 350+ coachees | 5+ years of consulting experience in London, Dubai and Istanbul
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Anonymous B replied on Nov 17, 2019

The best way to do is to break into simpler numbers wherever (numerator or denominator) large number exists.

E.g. 11/275

Step 1: 275 is the number you want to break --> 25 * 11 = 275

Step 2. Put it in fraction. Now, your equation becomes --> 11/ (25*11)

Step 3. Solve the new equation into simpler form --> 1 / 25

Step 4. Convert 1 / 25 into fraction (1 / 25) * (100 / 100) = 0.04, only if you cant do from Step 3 directly

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Francesco
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replied on Dec 01, 2019
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Hi Anonymous,

assuming you can approximate numbers, in this case you can find what is a relatively small percentage (eg 1%) and see how the number you have to calculate compares to that.

In this case, 1% of 275 is 2.75, which means 2% is 5.5. At this stage, you would probably notice that 11 is therefore exactly 4%.

Best,

Francesco

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Vlad
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replied on Nov 17, 2019
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School

Hi,

You should approximate it:

50% of 275 = 135

110 is roughly 40%, thus 11 is 4%

Best

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Antonello gave the best answer

Antonello

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