You may also like

problem icon

Pebbles

Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?

problem icon

Sweets in a Box

How many different shaped boxes can you design for 36 sweets in one layer? Can you arrange the sweets so that no sweets of the same colour are next to each other in any direction?

problem icon

Maze 100

Can you go through this maze so that the numbers you pass add to exactly 100?

Twenty Divided Into Six

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2
We had over seventy solutions sent in for this activity!

Miranda from Redmaids' High Junior School wrote this helpful introduction for the solutions:

There are thousands of different combinations to this puzzle, and this is what makes it seem so difficult - so if you want to narrow the answers down you need to try and use some simple maths to work out what the piles add up to. We’ll call it x . We already know that there are the numbers 1-20, and when added they make 210. This can be called y. What has this got to do with x? Well, we need six piles so we need to divide y by 6.  Now insert the formula into a division.
So x = 35! This is very useful. All we need to do is sort the numbers into six piles that each add up to 35. Wait! The six piles have to be unequal. If you did all different numbers of cards, you could have 1+ 2 + 3 + 4 + 5 + 6, which equals 21. 1 card is left over but we know 20, the biggest number, is too small! This means that although the piles are unequal, there need to be some piles with the same number of cards.
We need to get the total of the numbers of cards in each pile just right so that it adds up to 20. For example, 2 + 2 + 3 + 4 + 4 + 5 cards = 20 cards. That means there could be a solution to this combination.
So feel free to go and have an explore! Don’t worry if your cards don’t add up as there are still lots of ways that you can place them. Here is practical tip that it would be a very good idea to use: Don’t put the small numbers in big piles all the time because you need them to ‘fill in the gaps’ that the big numbers make e.g 19 + 5 + 1.

These are all the pupils and their school who sent in correct solutions:
Sahasra at Reigate Priory School;
Team Boss at Bede Burn School;
Stanley at St John's Primary, Basingstoke;
Dhianat at Holtspur Primary School; 
Jack and Daniel at Crossgates Primary School, Scotland;
Ioan and Kai at Abercanaid, Wales;
Gabo at King's College London in China; 
Joshua and Texas at Bandung Independent School, Indonesia;
Olivia at Marlborough Primary, Wales;
Callum and Micha, Owen and Tye, Thomas and Jessica at Jarrow Cross C of E Primary School; 
Jorja at Raetihi School, New Zealand;
Vivaan at Ridgeway Primary School;
William at Emmbrook Junior School;
Andrew, Nick, Isabelle at Drummoyne Public School, Australia;
Monty at Mawdesley St Peter's; 
Oliver at St John's CEP, Sevenoaks;
Dylan at Plantation Primary;
Lola at Brookfield Primary School;
Miranda at Redmaids' High Junior School;
Dylan at Wharncliffe Side Primary School, Sheffield;
Harvey and Kieran at Westcott Primary School, Hull; 
Shriya at International School Frankfurt, Germany;
Ritesh and Khushi, Felix and Jasmine, Eaven and Izzy, Neya and Dhiyaan, Molly and Dylan, Shania and Cameron, Martha and Mya at Highcliffe Primary School; 
Zara and Gemma at St Cuthbert Mayne; 
A pupil at Barrs Court;
Niamh, Amani, Manahal and Tamara at Saint Augustine's Priory;
Riley and Milan at Lyneham Primary School, Australia;
Matthew, Logan and Hayden, Ben and Harry, Kieran and Owen at Ashfield Junior School;
Naa, Isobel, Thomas, Josh and Isla, Phoebe, Amelia, Jessica and Lily at Thorpe Primary School;
Harvey and Kieran at Westcott Primary School, Hull;
Elsa at Meavy C of E Primary School.

Here are all the correct solutions that came in, you can view them more clearly here.jpg 


A last minute new solution came in that was too late for the chart from Thomas and Harry from The Academy of Cuxton Schools; 20, 11, 4;  19,15,1;  18,14,3;  17,10,8;  16,12,7;  13,9,6,5 and 2.
 

Dhian from Holtspur Primary School had an interesting adventure with this activity. He wrote:

The groups are: 12, 8 and 2, 7, 6, 5 and 10, 1, 9 and 3, 17 and 20 and 4, 16.
These are the 6 groups and the total they add to is 20. I have not not used all of the numbers from 1 to 20 as the puzzle did not state this (hope that's ok!).

That's an interesting variation!

Well done all of you who sent in good solutions which form part of the chart above.