Really why is he interested in tipping?

The other night at dinner, my teenager asked her preteen brother why he was so interested in what I gave for a tip at lunch. I shared with her the fact that he now puts the tip on our bill when we go out to dinner. Here is how this started:

Last year I started having my preteen figure out what the tip was on our meals when we went out to eat. The family eats out a lot and I thought this would be great practice at percents and fractions. There are several reasons for having him do this. The main ones are to have a grasp on how much things cost and practice with practical math applications.

We worked on taking 10% of the total bill ( $49.83) which would be $4.98Then you take the $4.98 and double it to give you 20% of the bill to give you a 20% tip.If you want to do a 15% tip you divide the 10% tip ($4.98) in half $2.49 and add it to the 10% total making the 15% tip=$7.47

The majority of the time we round up the change portion to a whole number. This also helps my kidlet understand that things do cost more than just the list price.Here is a website I found regarding tipping.

What do you do with your kids to encourage teaching math skills in every day environment