Clock Face
From Jonathan at St Peter's College, Adelaide, Australia:
"Dear Nrich, I have found a solution to Clock face. If you draw a
line from 12 to 6 and you go 12 minus 6 = 6. Every number greater
than 6 is like this. With any number 6 or under, you must add 6!
Cheerio!''
Sakunthala has sent us a solution for the second half of the
problem: If you draw a line begining before 11 and ending before 3,
the total on one side of the line is half the other side.
Absolutely right. Well done!