Probability
Probabilities are represented by numbers between 0 (impossible) and 1 (completely certain). Probabilities are abbreviated using the lower-case letter p The value p=0.5 means a 50/50 chance; the value p=0.25 means a 1-in-4 chance; the value p=0.999999… means almost certainly; the value p=0.000000…1 means very rarely.