Copyright © University of Cambridge. All rights reserved.

'Thirty Nine, Seventy Five' printed from https://nrich.maths.org/

Show menu

Thank you for working out the money in our birthday present pot! We have had lots of suggestions from St Aldhelms School:

Matthew:

20 * £1.00 = £20.00
20 * 50p = £10.00
44 * 20p = £8.80
3 * 10p = 30p
13 * 5p = 65p
Total   £39.75

Justin:

7 * £1.00 = £7.00
48 * 50p = £24.00
43 * 20p = £8.60
1 * 10p = £0.10
1 * 5p = £0.05
Total   £39.75

Emma:

10 * £1.00 = £10.00
50 * 50p = £25.00
10 * 20p = £2.00
25 * 10p = £2.50
5 * 5p = 25p
Total   £39.75


Daniel from Ysgol Dyffryn Dulas Corris found an other possible combination:

Daniel:

1 * £1.00 = £1.00
72 * 50p = £36.00
8 * 20p = £1.60
4 * 10p = 40p
15 * 5p = 75p
Total   £39.75


When you pay for things in shops you can give the money in lots of different ways, but in this case you had exactly 100 coins. Perhaps it is a little unexpected that there are all these different solutions. Are there any more?