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Combinations (nCk) worksheets Grades 11–12

Evaluate combinations with the factorial formula, cancelling first.

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How to do it

nCk = n! ÷ (k!(n − k)!). Cancel before multiplying.

7C2=217C2 = 21
7×62×1=21\dfrac{7 \times 6}{2 \times 1} = 21nCk = n! ÷ (k!(n − k)!)

Example problems

  1. 9C5=9C5 =
  2. 5C2=5C2 =
  3. 10C2=10C2 =
  4. 4C2=4C2 =

Sequences and series

  1. Arithmetic sequences
  2. Geometric sequences
  3. Writing the formula for a sequence
  4. Sigma notation
  5. Arithmetic series
  6. Geometric series
  7. Infinite geometric series
  8. Combinations (nCk)
  9. The binomial theorem