For problems involving percent, it can be helpful to understand that "percent" means "per cent" or "per hundred". ("Per" means "divided by.")
In symbols, the "%" symbol is just a shorthand way of writing "/100".
So 6.5% = 6.5/100. You can get rid of the decimal point by multiplying both numerator and denominator by 10. Doing that gives
... 6.5% = 6.5/100 = 65/1000 (sixty-five thousandths)
Now, you know the way to write sixty-five thousandths as a decimal is
... 65/1000 = 0.065
Compare this result to any problem in which you are dividing by 100. For such a problem, you simply move the decimal point 2 places to the left.
... 3456/100 = 34.56 . . . . . . for example
Or, in your case
... 6.5% = 6.5/100 = 0.065 . . . . . decimal point is moved to the left
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Then 6.5% of $300 is ...
0.065 × 300.00 = 19.50
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You can also rearrange the problem to
... 6.5% × 300
... = 6.5/100 × 300
... = 6.5 × (300/100) . . . . use the associative property of multiplication
... = 6.5 × 3
... = 19.5