100 / 5 = 14 
30 + 30 = 60
50 * 2 = 120
100 - 5 = ?

What is the answer, that should be in place of the question mark?

  • $\begingroup$ I think it's 64. Pressed for time, no time to give informative answer, so it;s a comment. $\endgroup$ Nov 14 '16 at 15:06
  • $\begingroup$ I am unsure if i should say if it was correct or incorrect in the comments. Could you also elaborate a bit more later on on how you go there? $\endgroup$ Nov 14 '16 at 15:09

The answer is


The trick is

All numbers are given in Octal

Some deductions I made:

30+30 works, so the math is probably right in a different base,
50*2=120 got me to Octal, which confirmed my suspicion based on the question title.

Incidentally, 100/5=14

Works in Integer Division, in regular mathematical division, it results in a remainder.

  • $\begingroup$ ha, ninja'ed because I was taking the extra time to explain that the division on the first line had to be taken as truncating :-). $\endgroup$
    – Gareth McCaughan
    Nov 14 '16 at 15:09
  • $\begingroup$ Oh, good point, I'm kinda used to Computer-style division, I'll comment that in $\endgroup$
    – Sconibulus
    Nov 14 '16 at 15:12
  • $\begingroup$ This is indeed right $\endgroup$ Nov 14 '16 at 15:13

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.