600.003
200,000.003
It is a decimal number: 0.304
57.00374
0.00375
Fifteen and three hundred thousandths
23 and 56/10000
Three thousandths is 0.003.
Three ten-thousandths is 0.0003.
Twelve and three thousandths.
You would write forty-three thousandths as: .043.
I would write three and seventy-one thousandths.