About percentages

Hi there, 

in short, get familiar with percentage calc and fractions and practice rough estimation maths to become quick at it.

Re your specific questions:
1. Tesla captures ⅓ of the market: look at Tesla share → 7,200. Look at total market. 21,100. Simplify via fractions → 7/21 is roughly one third.
2. Total sales are growing by 20%:  Q32015 sales are 21,200, Q3 sales are 25,400 → benchmark 10% of baseline = roughly 2000 → 21k + 2x 2k = 25k roughly.

In general, don't worry, if yo're unsure, you can always just jot down the numbers and calculate on paper. Yet, ff you'd like to learn more about how to become quick at at mental maths through shortcuts, feel free to reach out. 

Hope this helps.

Regards, Andi

Hi there,

I think this is an interesting question that may be relevant for many people. I would be happy to share my thoughts on it:

• First of all, I would like to assure you that unless it is very simple math, you are not required to do all the calculations in your mind. While this is certainly a valuable skill to have, it is not necessary to succeed in interviews. Instead, what truly matters is whether you can identify the right insights from a chart and interpret them correctly.
• Moreover, I would advise you to practice rough calculations. For example, 5% is half of 10%, and 10% essentially means moving the decimal point one place to the left. The same applies to 25%, which is half of 50%, and 20%, which is 1/5.

If you would like a more detailed discussion on how to address your specific situation, please don't hesitate to contact me directly.

Best,

Hagen

Agree with the other coaches who have answered thus far, and want to add the following:

• There are tools out there that allow you to practice mental math and estimation. I know many candidates have found Victor Cheng's to be helpful (you have to make a free account)
  • Use the Estimation Math setting
  • Ignore the comparisons offered during the practice runs, I've found them to be misleading
• The way you explain your math process is often more important than the math itself. Happy to discuss this further if helpful

Best of luck with your preparation!

Hi there,

Please remember that, yes, it's important to be able to eyeball numbers. However, also note that you will often still have to do calculations on paper to get exact numbers. Both are important and both are used differently depending on the situation.

Please also remember that in casing there's never “a trick”. There are many tricks and lots of practice that, over time, when done the right way, add up to you being an effective caser. Hire a coach if you want to make sure to learn all of these.

For your ⅓ of market share question, you can just see it. Look at that chart. Tesla is taking up about ⅓ of the space. Personally, I would literally say “It seems Tesla has between ¼ and ⅓ of the market”

On the same question, 9 times 3 is 27. That means 9,000 out of 25,000 is about ⅓

For the growth of sales, 6,000 to 9,000 is a 3,000 difference. 3,000 is half of 6,000 therefore, sales are growing 50%.

One useful way to approach these types of exhibits is to recognize them as easy to convert fractions: 

- First, round these numbers to whole numbers, e.g., you see in the chart, the total is 25400 on the right hand side chart - round it off to 25000, do the same for the stacked bars

- Second, you should be very comfortable with converting fractions to numbers and vice versa. E.g., after converting those numbers to whole number: such as 9000/25000 = 36%, it should click immediately for you. 

- Third, qualify your response: Going off the 36% example, you should say “ Company A holds close to/approximately 40% of the market”, you never speak in absolute terms in interviews

Hope that helps! 

Dear applicant,

A) ideally simply Google this question try out five solutions and see which ones are easiest for you and enable you within a few minutes to do the math easily, such as looking for increase, a change or a meaning. You can also practice the quick math on preplounge quickly and find answers of how to do this fast for yourself

B) Most importantly though watch out in cases, often the meaning is more important than the number itself, decide what conclusions you would like to draw or can likely be drawn and answer directly with these, or if you can't find the number say it is more than or between a, b, c.

I would gladly help you succeed. Have a wonderful interview time 

Best regards.

Hello,

I would recommend using RocketBlocks as they have some great resources on improving mental math skills - such as approximations. 

After that, it is just a matter of practising a ton of drills :)

Hope this helps!

Rushabh

There's no trick. There's doing a lot of practice with division and percentages.

25 is a 4 increase over 21. 4 /21 is roughly 4/20 = 20%. There's no trick in this, just being accustomed to doing mental math.

Tesla has 9.4 (which is about 10) in 25, is a bit less than 40%. 10/25 = 40%. There's no trick in this, just being accustomed to doing mental math.

Hello,

Fractions help alot as other coaches have mentioned, as does practice. In addition to the resources that are mentioned, you could also come up very easily with a simple excel sheet that randomly generates problem sums for you to practice. 

All the best!