Decimal odds
Total return per unit staked, including the stake: 2.10 returns $2.10 for every $1 bet, implying a 47.6% probability.
Decimal odds are the cleanest format for arithmetic: implied probability is 1 divided by the odds, and an arbitrage exists when 1/oddsA + 1/oddsB is less than 1. They are standard in Europe and on betting exchanges, and most arbitrage calculators use them.
Measured on ArbMonster: Odds converter
Related terms: American odds · Implied probability · Dutching