I'd like to say Hi to forum members with this fun approach presenting numbers from 1 to 12 with one number only. It's a well known construction of 9 time table you can find from Internet. However, nine is nothing special in this case, but you can do same trick with other numbers. So I attached files for numbers from 1 to 9 plus sigma presentation of the clock.
Ideally you would use same number three times on each calculation. This is fulfilled on many cases, but there are exceptions, mostly because visual reasons. I have used basic math operational symbols here with no strict limit, what you can actually use. So task is a little bit ambiguous. Especially in case of using nearest integer, summation and addition notation.