Twelve thousand and twelve thousandths written as a decimal is 12000.012
It is 12000.012
Seven and seven hundred twelve thousandths would be written as 7.712The "and" tells you where the decimal goes, "thousandths" tells you how many places there will be in the decimal part of your answer (3 decimal places for thousandths), and seven hundred twelve tells you how many thousandths there will be.
Six hundred and twelve thousandths is written 600.012
12.905 is written as twelve and nine hundred five thousandths.
12,000.012
0.012
4.01612
12,000.012
0.0012
0.812
80.0012