# IQ test number sequence

I found this on an online iq test, and am stuck on it:

8442, ?, 20.50.50.5, 4114, 410.251


I have no idea what the dots mean here, I also googled the test and someone says it is 9642 (which might or might not be the answer) without explanation.

Any ideas? Thanks!

• from which online IQ test, exactly? Sep 7, 2018 at 14:00
• @Kevin L : This one:hriqtests.com/insc-2017
– z100
Sep 7, 2018 at 15:25
• should we neglect zero's and dots? or Dot means multiplication? Sep 8, 2018 at 0:19
• @CR241Not sure what dots mean, but definitely means something since for all the other questions there's not really any useless information. Sep 8, 2018 at 4:50

It is 2124.

Treat the dot as a decimal point (as usual).

Insert spaces to distinguish numbers:

8 4 4 2
2 1 2 4
2 0.5 0.5 0.5
4 1 1 4
4 1 0.25 1

Explanation:

In the following row the 1st number is 1st divided by 2nd, 2nd is 2nd divided by 3rd, 3rd one is 3rd divided by 4th and 4th is 1st divided by 4th.

• Awesome work, would've never thought of that. Thanks! Sep 11, 2018 at 2:21