Question 270462
How many license plates are possible to make if (a) digits and letters can be repeated, (b) and digits and letters cannot be repeated.
a) 4 digits followed by 2 letters
b)6 digits followed by 3 letters

Label a digit as d and letter as l
a) ddddll
If you can repeat:
nine options for each d and 26 options for each l
9*9*9*9*26*26=4435236
Cannot repeat:
nine options for the first d, eight for the second, seven for the third, and six for the fourth; 26 for the first d and 25 for the second
multiply it all:
9*8*7*6*26*25=1965600
b)ddddddlll
Repeat:
Use same way (nine options for each digit and 26 for each letter)
9*9*9*9*9*9*26*26*26=9340607016
Cannot repeat:
Same pattern:
9*8*7*6*5*4*26*25*24=943488000
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