The screenshot looks like someone is passing out. That could have happened to Einstein, too1
The multiple of 10 approximation is pretty close, but the 3d6 roll gets a little more complicated because of the statistics used in setting the IQ scale. The standard IQ test is normalized where the mean score is 100, and the standard deviation σ is usually 15. the Bell curve is shown here: https://en.wikipedia.org/wiki/Standard_deviation#/media/File:Standard_deviation_diagram.svg
If you do the 3d6 numbers in a percentile probability table it looks like this:
Roll Freq Prob
3 1 0.5%
4 3 1.4%
5 6 2.8%
6 10 4.6%
7 15 6.9%
8 21 9.7%
9 25 11.6%
10 27 12.5%
11 27 12.5%
12 25 11.6%
13 21 9.7%
14 15 6.9%
15 10 4.6%
16 6 2.8%
17 3 1.4%
18 1 0.5%
So you just add up the 3d6 probabilities and then compare that result to the Bell curve in terms of mean + standard deviations.
IQ: Mean 100, std dev 15
IQ 115 score = adds up to about 84% percentile on the wiki Bell curve, which is about a 14 in D&D terms via adding up the 3d6 probabilities.
See, you are smarter than you may have thought!
