What's the square root of 18.5

We can't square root such a number in a standard way because nothing powered by 2 may give us 18.5. However we can find a rounded decimal with a lot of digits on the right hand side of the decimal point. In this case it will be:

√18.5 = 4,3011626335213133858647367675249

We can round it further so it looks much nicer:

√18.5 ≈ 4,3

Note that (4,3)² gives us 18,49, so it's a pretty close rounding.