"'The Two Tenners', which utilises Alexander's 'Subconscious Switch', is one of the most breathtakingly ingenious routines I've ever come across. It's practical, brilliant and utterly baffling, and could be a stand-out item in any show or performance."
- Ian Rowland

This is Marsh's unique method for knowing the serial number of a spectator's bank note. A few different handlings and presentations are discussed each using his ingenious method - The Subconscious Switch.

Each presentation uses nothing more than two bank notes - yours and the spectators, and works anywhere with any currency and any denomination.

Both bills stay in view the entire time and there are no secret switches, devices, or sleight of hand used in this routine.