If you mean 21/1000 then it is 0.021 as a decimal
6.00021 The first decimal place is tenths, then hundredths, thousandths, ten-thousandths, hundred-thousandths, etc. 21 hundred-thousandths must end in the hundred-thousandths place.
21/1000
21.012
No! 21cc is 21 cubic centimetres and is a measure of volume. 21mg is 21 milligrams (21 thousandths of a gram) and is a measure of weight.
21 thousandths = 0.021 = 21/1000 in fraction
hundred thousandths = 1/100,000 → 4 and 21 hundred thousandths = 4 21/100000 = 4.00021
0.021 = 21/1000 in fraction
0.021
If you mean 21/1000 then it is 0.021 as a decimal
6.00021 The first decimal place is tenths, then hundredths, thousandths, ten-thousandths, hundred-thousandths, etc. 21 hundred-thousandths must end in the hundred-thousandths place.
21000 is not a decimal. If you meant 21 thousandths, this would be 0.021
0.021
0.00021
21/1000
21.012
21/1000 or 0.021