Examples
Examples
Try the starting example
- Tosses
- 4
- Head probability
- 0.5
- Required heads
- 2
- Probability
- 0.375
Try another scenario
- Tosses
- 5
- Head probability
- 0.5
- Required heads
- 2
- Probability
- 0.3125
Calculation method
Calculation method
Probability
(combinations(a,c)) × b^c × (1-b)^(a-c)
Symbols and units
- a
- Tosses
- b
- Head probability
- c
- Required heads
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Calculation steps and notation
combinations(n, k) = n! / (k! × (n−k)!), counting unordered selections without replacement. The implementation uses exact integer products and divisions, with n at most 500.
Assumptions & limits
Assumptions & limits
- Each toss is independent with the same entered head probability.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.
Further reading
Background reading; this does not imply endorsement or independent review of SumFizz.