How would you write three and nine hundred one thousandths as a decimal?

Answer 1

Depends on exactly what you means as it's slightly ambiguous from the question. If its 3.(900/1000) then it's simply 3.9 as 900,1000s is exaclty the same as 9/10 or nine tenths.

Or you could mean 0.903 which is 903 thousands but not sure if this is what you mean.