What Is Probability?
Probability is a measure of how likely an event is to happen, expressed as a number from 0 (impossible) to 1 (certain), or as a percentage. For equally likely outcomes, probability = number of favorable outcomes ÷ total number of possible outcomes. The chance of rolling a 6 on a fair die is 1/6.
Basic Rules
For independent events, the probability of both happening is the product of their probabilities. The probability that an event does not happen is 1 minus its probability.
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Random Number Generator
Unbiased random numbers in any range, with or without repeats.
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Percentage Calculator
Three calculators in one: percentage of a number, percentage of total, and percentage change.
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Fraction Calculator
Add, subtract, multiply, and divide fractions and mixed numbers, with steps.
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🔗 Related Terms
More Math & Statistics Terms
- Absolute Value
- Confidence Interval
- Correlation
- Exponent
- Exponential Growth
- Grade Point Average (GPA)
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Last updated: September 27, 2026. This definition is for general educational purposes only. It is not financial, investment, tax, legal, or medical advice, and it does not recommend any product or course of action. For decisions about your own situation, consult a qualified professional.