## Wednesday, May 11, 2011

### Here's Why Math is Important

Class question: What percents are they actually calculating.

Wayne Keith said...

Ouch, I wonder how many people just blindly pay what it says? Looks like about 21.4%, 25.6%, and a whopping 28.5%! I guess that's what you get for letting someone else do your math. Makes me wonder if it's really accidental. I rarely work out a tip to the penny, though, on an approximately \$20 bill I'd just tip \$3 and be done with it.

Dave Hill said...

I'm guessing they're calculating based on a non-discounted price (e.g., without the BOGO or percent-off coupon that was presented). If so, that's actually a legitimate suggestion, if very poorly couched.

Jon Voisey said...

I'm thinking the same thing Dave. If this is a credit card receipt, then it wouldn't include the itemized list and as such, we shouldn't see those things. I wish I had contact info for the person that originated this so I could ask, but alas, this was posted on IAB anonymously.

Stephen Uitti said...

I always do the math myself. 10% is trivial to compute. 20% is twice that. 15% is half again of 10%. It's just not that hard. But gone are the days when i can do 20 digit mental arithmetic divides. Didn't keep it up.