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Australia has six coins that are commonly used – 5 cents, 10 cents, 20 cents, 50 cents, $1 and $2.

How many different ways can you make exactly 50 cents in Australian coins?

Scroll down for the answer!

 

 

Brainteaser answer

This problem takes a bit of organising to make sure you cover all the possibilities. One way is to start with big coins and work down.

First, the easiest solution: one 50 cent coin • 50

Next, there are two solutions with two 20 cent coins: • 20, 20, 10 • 20, 20, 5, 5

There are four solutions with one 20 cent coin: • 20, 10, 10, 10 • 20, 10, 10, 5, 5 • 20, 10, 5, 5, 5, 5 • 20, 5, 5, 5, 5, 5, 5

And finally, six solutions with no 20 or 50 cent coins: • 10, 10, 10, 10, 10 • 10, 10, 10, 10, 5, 5 • 10, 10, 10, 5, 5, 5, 5 • 10, 10, 5, 5, 5, 5, 5, 5 • 10, 5, 5, 5, 5, 5, 5, 5, 5 • 5, 5, 5, 5, 5, 5, 5, 5, 5, 5

So all up, there are 13 ways to make 50 cents!

For more brainteasers and puzzles for kids, subscribe to Double Helix magazine!

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Categories:

Brainteaser, Maths

Tags:

change, coins, mathematical sciences, money, number, problem solving

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3 responses

1. tt 19 January, 2023

   doesn’t help if your not in Australia but no hate 🙂

2. notmee 5 April, 2023

   *12 not 13

   1. David Shaw 5 April, 2023

      I forgot to dot point the 50 cent coin option! I’ll update it now

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