Choose function (nCr)

_nC_r calculates...

• the number of ways to choose r things from n

• the number of ways to choose n things from r

What could this calculation be used to find? Choose all possibilities!

• ₇C₂

• ₇C₅

• ₅C₂

• ₅C₇

Without a calculator, evaluate:

₈C₂

• 56

• 28

• 21

• 35

Without a calculator, evaluate:

₁₀C₃

• 120

• 135

• 210

• 30

Without a calculator, evaluate:

₁₂C₃

• 220

• 66

• 495

• 1980

Without a calculator, evaluate:

₁₂C₄

• 220

• 792

• 495

• 66

Without a calculator, evaluate:

₉C₂

• 36

• 84

• 18

• 252

Without a calculator, evaluate:

₈C₃

• 56

• 280

• 168

• 252

Without a calculator, evaluate:

(₁₉C₁₀) - (₁₉C₉)

• 0

• 1

• 19

• 171

Without a calculator, evaluate:

(₁₀C₁) - (₉C₁)

• 0

• 1

• 9

• 10