Using the formula, to calculate percentage, you must divide 450 (part) by 600 (whole) and multiply by 100.
Now enter the value 450 on the calculator, then hit the division sign and enter 600. After this, hitting the '=' sign will give you the value of the ratio=(450/600).
Now, hit the 'X' sign and enter 100. Hit the '=' sign again to know the percentage.