© 1999
T
EXAS
I
NSTRUMENTS
I
NCORPORATED
TI-30X
Ù
S: A Guide For Teachers
69
Combination (nCr)
H
You have space for 2 books on your
bookshelf. You have 4 books to put
on the shelf. Use this formula to
find how many ways you could place
the 4 books in the 2 spaces.
4 nCr 2 = x
A
B
C
D
AB and BA
count as only 1
combination.
AB AC AD
BA BC BD
CA CB CD
DA DB DC
Press Display
4
H
"
nPr
nCr
!
¹
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DEG
2
<
4 nCr 2
'
6.
DEG