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Mental math app for practising fractions/percentages

case math fast math fraction math mental math percentage
Recent activity on Aug 08, 2020
7 Answers
6.3 k Views
Richard
Proficient
asked on Apr 13, 2020

Hey guys,

If you want to practice mental math fractions and percentages for your case interviews, I've released an app called 'Case Math' on the iOS store to do just that. https://apps.apple.com/us/app/case-math/id1507653375?mt=8&ign-mpt=uo%3D4

I've designed it to focus only on fractions for three key reasons:

1) Fractions are involved in many calcs: market sizing, margins, market share etc.

2) Fractions are typically harder and less practiced than other operations - addition, subtraction & multiplication

3) I couldn't find other mental math apps that allowed practice using non-exact answers. E.g. in a case you'd typically be allowed to estimate 6/17 to within 5-10%

I've found it helpful to incorporate into my daily drills and thought others might as well. If you give this app a try, I'd love to hear your thoughts on it - if you think it's useful, and what other features you think would help improve it.

Thanks,

Richard

(edited)

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Luca
Expert
Content Creator
replied on Apr 13, 2020
BCG |NASA | SDA Bocconi & Cattolica partner | GMAT expert 780/800 score | 200+ students coached

Hello Richard,

Thanks for sharing! Actually I have many candidates that struggle with mental math, I will take a look to your app.

Best,
Luca

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Richard on Apr 13, 2020

Amazing thanks so much Luca, I'd be keen to hear if you think it would help other candidates (if you send me a message I can give you a promo code to download it)

(edited)

Giacomo
Expert
replied on Apr 13, 2020
Bain & Company | MBA | Real Case Simulation

Hi Richard,

Actually I think that this youtube channel is one of the best to learn some tips for faster mental math. During my interviews it helped me a lot, especially the videos about fraction and moltiplication.

https://www.youtube.com/watch?v=Rgw9Ik5ZGaY

In addition, do not be worried too much on that, of course you have to be fast on mental calulcation but during inteviews you can take time and put down the numbers to help you for more difficult calculation. So take your time for harder calculation and avoid stupid mistakes!

Good luck!

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Clara
Expert
Content Creator
replied on Apr 13, 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut

Thanks, I will try it out and let you know.

What is the value proposition vs., for instance, a good Youtube video? (that they are plenty and free)

Cheers,

Clara

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Richard on Apr 16, 2020

Thanks Clara!! Much appreciated. For me the value proposition offered by the app is simply the convenience for practicing drills. Youtube was awesome for learning the theory of fast math but I found it quite annoying to set up practice drills to apply those skills….especially for fractions. The motivation to make this was actually from me setting up a random fraction generator in Excel on my PC to help me do drills…which was not a great user experience. With the app I can practice anywhere / anytime I have a couple of minutes… I guess that's where I see the value!

Thomas
Expert
Content Creator
replied on Apr 13, 2020
150+ interviews | 6+ years experience | Bain, Kearney & Accenture | Exited startup| London Business School

That seems like a great app that will help many people! I used a few online tools when I was preparing that filled the need. This was my go to tool: https://arithmetic.zetamac.com/

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Antonello
Expert
Content Creator
replied on Apr 30, 2020
McKinsey | NASA | top 10 FT MBA professor for consulting interviews | 6+ years of coaching

In interviews the aspect which causes more errors is pressure: start to solve calculations with strict time constraint. For longer formulas always share the calculation structure with interviewer before starting to write down the numbers: this helps to take time, to reduce the pressure and gives you the opportunity to receive a first feedback by the interviewer avoiding wrong calculations.

I recommend practicing with:

Best,
Antonello

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Jemima replied on Aug 08, 2020

Thanks for sharing, have been using it to practice and like how you only need to get the answers within a range of accuracy. Perhaps you could incorporate other consulting math drills for a future release.

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2
Anonymous replied on Jul 17, 2020

Dear Richard,

Thanks for sharing!

Very valuable instrument

Best,

André

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