This film explains how to count cards in black jack to gain an advantage. Every suit in a deck is said to add or minus up to a count of zero. So the whole deck has a count of zero. There's some synthesized high speed music in the middle while the presenter extracts the spades to show us. Ten to ace have a value of minus one. Seven, eight and nine have a value of zero and the numbers below seven have a value of plus one. The pluses and minuses cancel each other out to produce zero. The numbers dictate the chances of winning at blackjack because you know roughly how many face cards are likely to appear in the following round.