I see no reason to capitalize it. In general, you capitalize something if it is the name of a single, unique thing (for example, the name of a person or country); or if something is considered sacred or otherwise important. There are a few additional cases when you capitalize something, but I don't see how any of them would apply in this case.
No you do not need to.
2.5 million dollars
2224.4 million dollars means 2224.4 times 1 million dollars 1 million dollars is $1,000,000 → 2224.4 million dollars = 2224.4 x $1,000,000 = $2,224,400,000 which is two thousand million, two hundred and twenty four million, four hundred thousand dollars, but as the USA uses the short scale (based on power of a thousand plus one) it can be read as: two billion, two hundred and twenty four million, four hundred thousand dollars
Two million Four hundred thousand dollars.
0.02 x 20 million = 400,000 dollars
No you do not need to.
Yes, the phrase "one million dollars" should be capitalized because it is a specific monetary amount.
Two million and 00/100 dollars
$2,200,000 or two million two hundred thousand dollars.
2.5 million dollars
One million, two hundred thousand dollars
2224.4 million dollars means 2224.4 times 1 million dollars 1 million dollars is $1,000,000 → 2224.4 million dollars = 2224.4 x $1,000,000 = $2,224,400,000 which is two thousand million, two hundred and twenty four million, four hundred thousand dollars, but as the USA uses the short scale (based on power of a thousand plus one) it can be read as: two billion, two hundred and twenty four million, four hundred thousand dollars
two million five hundred thousand dollars
Two million Four hundred thousand dollars.
540 million dollars
To two decimal places it is about 36.71%.
0.02 x 20 million = 400,000 dollars