Probability & Statistics Calculators

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Permutation & Combination Calculator – nPr & nCr

Calculate permutations and combinations easily. Input n and r to see the number of ordered arrangements or unordered selections, with formula and steps.

Math calculator combination nCr nPr permutation

Normal Distribution Calculator – PDF, CDF & Z Probabilities

Explore the normal distribution: compute probability density, cumulative probability, and tail probabilities for a given z-score or x value with interactive plot.

Probability calculator normal distribution probability z-score