From an iq test online I have trouble doing the problem:

357, 1251, 152, ?, ?, 0

I tried a common trick to ignore the spaces and add commas elsewhere but it doesn't do anything.

The answer is

25, 01

Does anyone know why?

  • $\begingroup$ Ignoring the first two gibberish, in the 152 there is a 2 and a 25 and the zero's last two should also be flipped like the 152 so you use a one, I guess? $\endgroup$
    – Duck
    Aug 25, 2018 at 2:48
  • $\begingroup$ @u_ndefined I tried submitting it appears that it's not, thanks for picking up. $\endgroup$
    – simonzack
    Aug 25, 2018 at 5:17

1 Answer 1


The leading zero that got edited out is definitely relevant, the puzzle won't work without it.

You get the next number by

taking the first digit of the previous number, multiplying it by each of the other digits in turn, and writing the results together, backwards.

For example, to get from 357 to 1251,

     3*5, 3*7 (multiply first digit with all others)
     15   21  (read backwards)


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