[KillerGremlin]

Not being able to calculate tip is a pet peeve of mine. I have become "the tip guy" amongst several of my friends who are either too lazy or too dumb to figure out tip. Put your fucking tip calculator away though, you look like a jackass when you whip your phone out to do 2nd grade math.

The article is true though...if you can multiply by 1 you can figure out the tip.

1 x 1 = 1
1 x 2 = 2
1 x 8===D = 8===D
etc.

$47.36 x (10%) or .1 = 4.736
multiply by 2 for a 20% tip, or divide by 2 (or multiply by 1/2) and add that for 15%.

and for simplicity sake, if the waiter was good I would just round $4.736 up to $5. If the waiter wasn't good round down to $4.50 or $4.