The second caution is that the step from division to multiplication should be a single expression on a calculator in which the quotient is not expressed but is held in the calculator and the multiplication function applied.
For example:
Correct Method: $6,000,000 divided by $9,000,000 multiplied by $4,000,000 = $2,666,666.67
Incorrect Method: $6,000,000 divided by $9,000,000 equals 0.67, and 0.67 then multiplied by $4,000,000 equals $2,680,000.00
As these examples make clear, the calculation method can change the results dramatically.