Math Formulas
I’m going to keep math formulas and other things here for future reference.
Calculate a tip (US).
If the check is more than $30, lop off the last threee digits, and double the remaining number. The resulting tip always will fail between 15% and 20%.
Example: If the check is $87.46, take out the 7.46, and you’re left with 8. Double it for a $16 tip (18.3%).
To calculate the tip if the check is less than $30, round up to the next highest dollar (so $13.27 becomes $14), then double that and insert a decimal point for the tip ($2.80, or 21%).
Scott Janousek is a Mobile Developer, Gadget Geek, & CEO of Hooken Mobile in Boston, MA USA.
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