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We had a number of really thorough solutions sent in, here is a selction.
Firstly from Class 6 from St Helen's C of E Primary School:


We all had a go and we came up with various strategies to help you win:
1. Add or subtract numbers according to what numbers are left on the grid;
2.Try to put counters on numbers which are close to each other on the grid;
3. If going first, try and get a number close to the middle of the grid;
4. Sometimes take risks as it is all about luck;
5. Don't just go across, go diagomally as well;
6. Try to block your opponent's counters;
7. Keep silent - don't tell your opponent what you are going to do;
8. Try to work out your opponent's strategy as well.

We all enjoyed the game!

Next, Danish from Ryerson School in Canada sent his thoughts:

My solution was to cover four positive integers in a "U" shape near the top row. Then I would start covering the most negative integers I could before the computer could because it usually tries to cover the same +/- integers in the same row/column that you have done before. That is how I won the game against the computer.

Pupils from Aldermaston School, namely Mary, Amelie, Hannah, Thomas and Sophie, wrote interesting things they had noticed/found out:

I found 12 hard to get because I didn't get many high numbers. I found 5 easy to get because there are lots of easy solutions to get 5.

The inside numbers are easiest to get because you can get three numbers in a row all around. The hardest numbers are on the outside because you can't get three in a row all the way round.

I find the inside numbers the easiest because you can get 3 in a row all around but the outside numbers are the hardest because you can not get 3 in a row all around.

The easiest number is 5 beacuse you have lots of different sums you can do to get to 5.

12 and -5 are the hardest numbers beacuse you can only do them once. 7 is the best number to aim for beacuse you can get to 7 in lots of ways.

12 is one of the hardest numbers when rolling a 1-6 dice, you should increase the height of a number on the chart and how many faces on the
dice.

Lastly Ollie from S.U.N School wrote:

The hardest numbers to get are -5 and 12. -5 is hard because you can only get it by using 1-6 and 12 is hard because you can only get it with 6+6.

The easiest numbers to get are 0 and 7. 0 is easy because you can make it six ways: 6-6, 5-5, 4-4, 3-3, 2-2, 1-1. And 7 is easy because you can make it six ways as well: 1+6, 2+5, 3+4, 4+3, 5+2, 6+1.