153678

The first time we played we used 11 numbers add the person who started won.

We worked out that the lowest amount of numbers you can use is 7 and the highest is 37, the highest is 37 because if you add 1 together 37 times you get 37 so the person who goes second automatically loses as they add a number to make the total even. We also found out that whoever starts will win because odd plus odd is even and odd + even is odd.

ps.your website deleted it twice so we had to keep retyping our work so we hope you put our maths up on Nrich =)