See what we can offer to your school
"SimpleStudy just makes sense...”
Get the best plan for your school
10 questions from this quiz
120120120
606060
Add different cases; multiply within
When order matters
When order doesn't matter
n!(n−r)!\frac{n!}{(n-r)!}(n−r)!n!
n!r!(n−r)!\frac{n!}{r!(n-r)!}r!(n−r)!n!
167,960167,960167,960
727272
Select your subjects, and get access to A+ resources today.