What is 10% of $300.000
Well, 10% is 10/100, which is a tenth, (1/10)
You have 300 dollars and a tenth of 300 dollars is 30 dollars.
When you divide a number by 10, all you do is shift the decimal poiont one place to the left.
So your answer is 30 dollars.
You have been writing the fractional part of a dollar amount as thousandths of a dollar, viz. $300.000
If you wish to keep the same specification, then the answer would be $30.000