Numbering failures do not announce themselves. Everything looks right in the box and goes wrong at the moment of the draw.

The duplicate

Two tickets with the same number means two people can claim one prize, and there is no way to resolve it that does not make somebody unhappy in public.

It comes from a numbering machine reset mid-run, or from two part-runs printed on different days without the range being carried forward. Both are prevented by stating the range on the job and checking books against it.

The gap

Less damaging and more embarrassing: numbers that jump, so your reconciliation of sold tickets against money taken never balances.

If you count your float by number ranges — and you should — a gap looks exactly like a missing book.

The overlap

Two events running the same range at the same time, usually because a roll left over from last year got used up first.

Order a separate range per event and label the outer boxes with it. It costs nothing.

The stub nobody could write on

Not a numbering fault, but it destroys the same audit trail: if the seller cannot write a name on the stub, the number in the drum identifies nobody.

Uncoated stock, every time, for anything that gets filled in.