Jane Street 1st round interview - any tips?

Hi,

So I have a phone interview with Jane Street sometime soon and I believe the finance interview will be highly quantitative. I am a math major as well as a finance major but haven't taken any major math classes yet; will be starting them next semester. So any tips on how I should prepare for the quant. stuff? Especially probability?

8 Comments
 
aachimpmental math is huge. even if you get all the answers right, if they feel you aren't quick enough, you're done.

I've been through quite a few interviews and I constantly get mental math questions like what's 4449, 3373 etc. Do they actually expect you to get those right or are they just looking for the process? I got the correct answer in an in person interview and I got a shocked look like I'm not suppose to actually get the number.

 
Best Response
The Tripster
aachimpmental math is huge. even if you get all the answers right, if they feel you aren't quick enough, you're done.

I've been through quite a few interviews and I constantly get mental math questions like what's 4449, 3373 etc. Do they actually expect you to get those right or are they just looking for the process? I got the correct answer in an in person interview and I got a shocked look like I'm not suppose to actually get the number.

yes, you are supposed to get those right. there is no process unless it's a special case where they want you to make it easier.

for example. a^2-b^2 = (a+b)(a-b). -> 4555 = 50^2-5^2 = 2475. different example, 1218.5 = 2012 - 1.512 = 222.

if you look up the Trachtenberg speed system of mathematics and perfect it, you can really fly through huge problems like 12513*25922, etc...

There's also Vedic math techniques that work for double and triple digit multiplication.

 

i have an interview with JSC next week as well. i'm a chemistry/econ dual major and math minor. i haven't taken any intense probability, stats, and comp sci courses, however. i'm pretty much going to treat this as a practice interview for my BB rounds. i know i have little chance against the five people they want who do have all these skills.

 

Vedic math is very good. In fact when I was in high school, I came up with a method to accelerate the squaring process. i.e what is 67^2? most people would use (70-3)^2 or (60+7)^2, but you could do this too; 67 = 42, and 77 = 49, so you have 4249+60*4 = 4489. you could work the other way around only it would be minus for anything lower than 65.

 

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