A Cha-Cha-Cha, also known as a “1-2-3 Best-Ball,” is a form of best-ball competition for 3 or more competitors, in which the number of balls to be scored begins with one ball on the first hole, two balls on the second hole, three balls on the third hole, then repeats for the remainder of the round:
Similarly, a Cha-Cha alternates between one ball on the first hole, two balls on the second hole, then repeating:
Handicap allowances for a Cha-Cha-Cha are typically calculated like a "2 Best-Balls of Four" competition, using a handicap allowance of 90% of Course Handicap for men and 95% of Course Handicap for women.
In some circumstances, it may be preferable to calculate handicap allowances for a Cha-Cha-Cha as a "1 Best-Ball of Four" competition - 80% of Course Handicap for men and 90% of Course Handicap for women.
In four-ball play, the USGA recommends reducing the Course Handicaps of higher-handicapped partners to a limit of 8 strokes greater than the lower-handicapped teammate, or reducing the Course Handicaps of all the teammates by 10% on teams with handicap disparities greater than 8 strokes. This adjustment makes for fairer play, but is not required.
Scorecard with 4 players and their Cha-Cha-Cha team score
In this illustration, the scorecard includes the individual scores of all the players and their calculated Cha-Cha-Cha team score. It's not required that all players return a score at each hole, unless the scores will be recorded for calculating a handicap.
Note on this scorecard that Mary's Handicap Index has been overridden to limit it to 40.4, the maximum non-local index for women. She has also recorded an "X" - disqualified or estimated score - on the 5th hole.
Net Cha-Cha-Cha scores using 90% & 95% handicap allowances
Illustrated here are the details of the net Cha-Cha-Cha team score. Note that on the 5th hole, where 2 balls were required, because Mary recorded an "X" score - disqualified or estimated, her score was not used to calculate the team's total.