It is a simple question.
How do you mentally calculate 5*(1.25)^5 fast?
It is a simple question.
How do you mentally calculate 5*(1.25)^5 fast?
Hi there,
Q: How do you mentally calculate 5*(1.25)^5 fast?
I believe you want to calculate an increase of 25% per year for 5 years.
The fastest approximation is probably with the rule of 72. Applying it, you get that you double in:
72/25 = 3 years
So after 3 years, you should be around 10.
Once you are there, you can either perform 10*1,25^2, or notice that you would double again in 3 years, so after that the result would be 20, as your new starting point is 10. Given you just have 2 iterations and not 3, the result should be somewhere between 15 and 16 (the actual result is indeed 15.3).
Hope this helps,
Francesco
Hi there,
I can definitively say you will not be required to do this.
By the way, your formula is already wrong. 125% does not translate into 1.25.
25% translates into 1.25
If I were to eyeball this, I would say it doubles every year and then some.
So, I'll double 5, 5 times, to get 160. Then, I'd double it one more time to account for the .25, getting 320
Hi there!
I'd challenge you whether that's actually needed in the interview.
Interviewers test your skills, not your knowledge, nor your mathematical prowess.
Basically, they want you to be decent with number, not a genius (otherwise they would be hiring math Phds).
Best,
Cristian
I think Ian and Francesco presented some good approaches here.
In general, with questions like this, the keys are going to be:
But I don't think you'll be required to do a calculation like this with some compounding on the fly. Maybe as part of the quantitative portion, where you can write it out and take a moment to calculate it.
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