Bunuel wrote:

HopefulOldie wrote:

How many 5 digit ( digit = 0 - 9 ) zip codes can exist in which atleast one digit is repeated ?

Zip codes with 5 digits (all five digits can be repeated):

10^5=100,000 if first digit is 0, its no longer 5-digit right?

Zip codes with no digit being repeated:

10*9*8*7*6=30,240 if first digit is 0, its no longer 5-digit right?

Zip codes with at least one digit being repeated: 100,000-30,240=69,760

so isn't the answer

Zip codes with 5 digits (all five digits can be repeated): 9 * 10 ^4 = 90000

Zip codes with no digit being repeated: 9*9*8*7*6 = 27216

Zip codes with at least one digit being repeated: 90000-27216 = 62784 ?

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