Gallery
Discover apps people built on Collabby by chatting. Run them, then remix to make them yours.
Combinations nCr
List every possible selection, divide permutations by r! to strip out order, and see the symmetry of choosing r versus leaving out the rest.
by Anonymous
Counting and Permutations
Fill the spots one by one, multiplying the choices that remain, and count the leaves of the tree diagram to confirm the multiplication rule and n!.
by Anonymous
Counting Fun
Tap objects one by one to count them, fill the basket to match a number, and compare which side has more.
by Anonymous
Counting Outcomes
Pair tops with bottoms in a grid and arrange number cards to count outcomes by the multiplication principle and n×(n−1).
by Anonymous