Maths-up before your next McDonald's visit (part 3)

PSLE Mathematics tuition

Time to reassess my objective. What I'm really interested in is the cheapest way to place my order. That means what I should be focusing on at this point is the price discrepancy among the different combos, rather than the absolute total amount.

With this in mind, I scan the price list again. The presence of some round dollar amounts and a healthy 'number sense' lead me to discover something. The difference in cost between the Fries + Coke combo and Wedges + Coke combo for all mains is $0.80.

best PSLE maths enrichment centre

That tells me there is no cost difference between the order configurations below:

  1. Main A a la carte + Main B-Fries-Coke combo + Main C-Wedges-Coke combo

  2. Main A a la carte + Main C-Fries-Coke combo + Main B-Wedges-Coke combo

Thus, the problem is now reduced to identifying the main that I should order a la carte.

I shift my attention to the next type of price difference: main a la carte and Fries-Coke combo (or Wedges-Coke combo).

best PSLE maths tuition centre

It's now clear which main that I should order a la carte. If like me, you pick correctly, you should be paying only $14.40. If you pick incorrectly, you could end up paying $1.45 more!

Parents, the next time you visit McDonald's, you might want to delegate the ordering to your children to give them a mental maths workout.

Note to self: To discuss with Mr Sim about adapting this scenario in an upcoming Maths lesson...

Subscribe to our newsletter to receive your regular dose of earth-shattering educational tips.