Input Parameters
n (total items)
r (items chosen)
Results
nPr = n! / (n−r)!
20
Arrangements (order matters)
nCr = n! / (r! · (n−r)!)
10
Selections (order doesn't matter)
Probability 1/nCr:
—
nPr / nCr ratio:
—
r! (arrangements):
—
n! value:
—
Step-by-step (nPr):
—
Step-by-step (nCr):
—
Presets
Formula Reference:
nPr = n! / (n−r)!
nCr = n! / (r! × (n−r)!)
nCr = C(n−1,r−1) + C(n−1,r)
nPr = nCr × r!
nPr = n! / (n−r)!
nCr = n! / (r! × (n−r)!)
nCr = C(n−1,r−1) + C(n−1,r)
nPr = nCr × r!