© 1999 T
EXAS
I
NSTRUMENTS
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NCORPORATED
TI
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34
Û
: A Guide for Teachers
85
Factorial (!)
H
Using the digits 1, 3, 7, and 9 only
one time each, how many 4-digit
numbers can you form?
4! = x
1
3
7
9
A
B
C
D
ABCD
BACD
CABD
DABC
ABDC
BADC
CADB
DACB
ACBD
BCAD
CBAD
DBAC
ACDB
BCDA
CBDA
DBCA
ADBC
BDCA
CDAB
DCAB
ADCB
BDAC
CDBA
DCBA
Press Display
4
H
"
"
nPr nCr !
¹
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--
<
<
4!
º
24.