If the number is accurate to two decimal places then you write it exactly as in the question.
It is already written in numeric form!
5,000,000
28" or 2'4"
You would write it as... 65,140,000 or 65 140 000
It is 21878.92, exactly as in the question.
It is already written in numeric form!
6M
470 = CDLXX
Exactly as in the question.
5,000,000
00610418452911
100 000
28" or 2'4"
12000 or 12 000
You would write it as... 65,140,000 or 65 140 000
6' 3"
You cannot. Inches are a measurement unit; here is no intrinsic numerical value.