Calculators - How to Play

About Calculators, from BoardGameGeek:

Calculators is a trick-taking game for 3 or 4 players. Players play through exactly four hands, but between each hand they will decide to place either x, +, or - between the two hands. At the end of the four hands, each player will have a small mathematical expression like "4 x (-3) + 2 - 1" which, when evaluated, gives the player's score. Whoever has the bigger number (positive OR negative) wins! Calculators can be played with a normal 52 card deck of cards. It may be helpful to mark the 5s and the Jacks, as these are worth +2 and -3 points respectively.