|ITV: 19 May 1956 - 18 January 1958|
Based on a popular American format, contestants pick a category and answer a series of questions increasing in difficulty starting at 100 and increasing up to 64,000.
Contestants first chose a subject category, and would then be asked questions only in the chosen category, earning money which doubled as the questions became more difficult.
The number of questions was dependent on the amount played for:
- 100: Single Question
- 500: Single Question
- 1,000: Two-Part Question
- 2,000: Two-Part Question
- 4,000: Three-Part Question
- 8,000: Four-Part Question
- 16,000: Five-Part Question
- 32,000: Six-Part Question
- 64,000: Seven-Part Question
At the 4000 level, a contestant would return each week for only one question per week. Upon reaching the 8000 level, they were placed in the isolation booth, where they could hear nothing but the host's words.
As long as the contestant kept answering correctly, they could stay on the show until they had won 64,000.
Originally, the top prize was 64,000 sixpences, or £1,600 in today's money. In late 1956, this doubled to 64,000 shillings, or £3,200.