It is fifteen thousandths, or 15/1000 of an inch. Just type it in as you see it in a calculator and you will get 0.015.
There is 1000 thousandths in an inch, so .015 is 15 thousandths of an inch.
I read it as 15 thousands. If it were .0015 I read that as 15 tenths.
That is the way I have been used to along with every machine shop I have ever
worked with reads it. It goes back to my school days as I was taught that
since the "5" is in the thousands column place holder the thousands is the
The "thousandths" nomenclature is the way to communicate with anyone who is going to design, inspect or manufacture your parts...unless you want to pay twice as much.
I am afraid your co-workers are correct it is fifteen thousandths.
15 hundredths is like saying 15 pennies. There are 100 pennies in a dollar so if you have 15 pennies you have 15 hundredths which is 0.15