+0  
 
0
37
1
avatar

Seven-digit telephone numbers are not allowed to begin with 0 or .1

I can only remember a seven-digit telephone number if the first three digits (the "prefix") are equal to the next three digits or the last three digits. For example, I can remember 389-3892 and 274-9274.

How many seven-digit telephone numbers can I remember?

 Jul 6, 2021
 #1
avatar+114012 
+1

9*10*10 = 900

900*10*2= 18000 posibilities

 Jul 7, 2021

6 Online Users

avatar
avatar