Standard deck: 52 cards = 4 suits (hearts, diamonds, clubs, spades) x 13 ranks.

• Red cards: 26 (hearts + diamonds)
• Face cards: 12 (J, Q, K of each suit)
• Aces: 4

Common calculations:

• P(drawing an ace) = 4/52 = 1/13
• P(drawing a heart) = 13/52 = 1/4
• P(2 aces from 52) = C$\frac{4,2}{C}$(52,2) = 6/1326 = 1/221
• P(at least one ace in 2 draws) = 1 - C$\frac{48,2}{C}$(52,2) = 1 - 1128/1326 = 33/221

Without replacement: Sequential draws change the denominator. Use multiplication rule: P(1st ace) * P(2nd ace | 1st ace) = 4/52 * 3/51 = 1/221.