Calculation (card game)
Calculation (also known as Broken Intervals, Hopscotch and Four Kings Solitaire) is a solitaire card game played with a standard pack of 52 cards. It is part of the Sir Tommy family of patience games. It has its origin in France, where it is known as La Plus Belle.
It offers more scope for skill than many similar games; a skilled player can win Calculation more than 80% of the time when "normal play" can allow winning 1 in 5 times. Good strategy typically sees players use 6s, 8s, and Queens early and 10s, Jacks, and Kings later; clever placement of cards in the waste is also critical, with some players reserving one waste pile for the Kings. Every game of Calculation Solitaire is winnable. The key is to focus on putting cards in the 'waste piles' in reverse order.