Verabrede dich zum Casen über das Meeting-Board, nimm an Diskussionen in unserem Consulting Q&A teil und finde gleichgesinnte Interview-Partner:innen, um dich auszutauschen und gemeinsam zu üben!
Zurück zur Übersicht

Math trick

Hi,

I am looking for a trick that could help me to solve the following type of division fast:

1,000,000 / 1,800

What methods would you recommend?

Thank you!

A.

5
2,3k
30
Schreibe die erste Antwort!
Bisher hat niemand auf diese Frage reagiert.
Beste Antwort
Gelöschter Nutzer
am 12. Nov. 2020

1,000,000 / 1,800 = 1,000,000 / (2,000 / 1.1) = (1,000,000 / 2,000) * 1.1 = 500 * 1.1 = 550

The first one is a bit of a simplification that introduces a small error, but unless the interviewer asks you specifically to calculate this precicely, this should be fine.

3
Anonym A
bearbeitet am 11. Nov. 2020

Personnally, I always go to things i know well. For instance here, 1 millions is half of 2 millions so you could go with two millions divided by 1800 and take half of your result.

Another way is to realize that 1800 is only 10% smaller than 2000. 1800= 90% *2000=90/100*2000.


So 1 000 000/1800 is actually 100/90* 1 000 000/2000=100/90*500.


Then it's easy because 100/90=10/9=1.11.
So 1 000 000/1800= 1.11*500=555.

Here i detailed all step but this can be done much easier once you realized that you can use 2000 and go from that.

Here is the detailled version for both calculation

2
am 11. Nov. 2020
Thank you! This sounds straightforward, but I don't understand this bit: So 1 000 000/1800 is actually 100/90* 1 000 000/2000=100/90*500. Why do we have 100/90? 90% is 90/100. But if I put 90/100 the result is wrong...
Anonym A
am 11. Nov. 2020
Hi Agatha, I added all the steps for both method to make my answer more understandable. Hope it helps.
am 12. Nov. 2020
Thank you!
Ian
Coach
am 11. Nov. 2020
Top US BCG / MBB Coach - 5,000 sessions |Tech, Platinion, Big 4 | 9/9 personal interviews passed | 95% candidate success

Hi Agata,

Great question!

  1. Cross out 0s
    1. 10,000/18
  2. Simplify
    1. 5,000/9 (cut in half)
  3. If rounding, get to closest, and add a segment
    1. 5,000/10 = 500
    2. It's a bit less (1/10), so add another 50
    3. = approx 550
  4. If you're not allowed to round, long division

What's that you say? I may have to learn long division and long multiplication? Yes. 100% :)

am 12. Nov. 2020
This is so easy, thank you!
Clara
Coach
am 12. Nov. 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut

Hello!

I would divide into 2000 instead. Then remove zeros, and simple division. 

Once it´s done, make it ~20% higher for the simplificaiton we made. 

Best,

Clara

Gelöschter Nutzer
am 11. Nov. 2020

Hi Agata,

There are plenty of threads and tons of tips and prep guidance for maths. Please search the forum. Have a look at these:

  • https://www.preplounge.com/en/consulting-forum/moltiplicationsdivisions-with-6-digits-numbers-estimation-math_tricks-2925
  • https://www.preplounge.com/en/consulting-forum/best-apps-for-mental-maths-4376
  • https://www.preplounge.com/en/consulting-forum/case-math-practice-6877
0
Ähnliche Fragen
Consulting
GMAT/Conceptual Questions in MBB Case Interviews?
vor 3 Std
Global
5
< 100
Beste Antwort von
Ihssane
Coach
McKinsey manager | -50% off first session | 7+ years in consulting| Case & Fit Interview Coach | Free intro session
0
5 Antworten
< 100 Aufrufe
+2
Consulting
Is more Math Drills the way to solve my issue?
am 2. Mai 2025
Global
7
200+
Beste Antwort von
Mattijs
Coach
Free 15m intro call | First session -50% | Bain| Hiring team | 250+ successful candidates
13
7 Antworten
200+ Aufrufe
+4
Consulting
Ecosystem in Solve went badly
am 11. Mai 2025
Global
2
100+
Beste Antwort von
Alessa
Coach
xMcKinsey & Company | xBCG | +200 individual & group coachings | feel free to schedule a 15 min intro call for free
4
2 Antworten
100+ Aufrufe
Wie wahrscheinlich ist es, dass du uns einem Freund oder Kommilitonen empfiehlst?
0 = Nicht wahrscheinlich
10 = Sehr wahrscheinlich
Vielen Dank für dein Feedback! Deine Meinung hilft uns, PrepLounge noch besser zu machen.