How many more chocolates can you exchange for?

Yesterday I heard an interesting mathematical question on radio posed by Mdm Teoh Poh Yew, an experienced international trainer.

Her profile as quoted from Class 938 Live website:

Profile: Teoh Poh Yew is a very experienced international trainer in the fields of creativity, Maths education and training of trainers. She is a dynamic and creative Maths educator who firmly believes that everyone can learn and enjoy this “dreaded” subject. She taught Secondary level Mathematics for 11 years and is now an independent teacher trainer. Her major interest is to transform Mathematics into a tool to develop creativity, enhance mathematical thinking and sharpen problem solving abilities.

Back to the problem:
A child has 29 chocolates. For every 5 chocolate wrappers, the child can exchange for another chocolate. How many more chocolates can the child exchange for?

Most students who are used to the rote-based teaching will immediately reply: “Five chocolates.”

Why?

Because 29 divide by 5 will give you the result 5 with a remainder 4.

But if you put this in the real life context, I believed you can get more than 5 more chocolates. In fact you can get a maximum of 7 more chocolates.

Can you figure out? Exchanging the 5 chocolate wrappers (that you had just exchanged) will give you 1 more chocolate. This wrapper can be used together with the 4 remaining wrappers to give you another 1 more chocolate.

Anyway Mdm Teoh make me realise that mathematics can be creative and realistic. And that I think I study too much of Singapore’s rote-based learning. Because I did not think very far when replying. In fact the dumb me was thinking I should go buy 1 more chocolate to exchange for 1 more chocolate.. no wonder I keep getting short-changed.