Question 1050878: How many seven digit numbers are there when 0 and 7 cannot be the leading number?
Answer by MathLover1(20850)   (Show Source):
You can put this solution on YOUR website! there are  digits from  to 
when and  cannot be the leading number, then there is  choices for the  digit and they are:  ,  , ,  ,  ,  , , and
there will be choices for  of the remaining digits, and we have:
or, you can do it this way:
Position: st.. nd .. rd.. th.. th.. th ..th
choices.... .... ...... .....  ...............
total number of choices: 
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