How many seven digit numbers are there when 0 , 5 and 6 cannot be the leading number?

Question

gorv · Answer

so at first place u can fill 7 numbers

gorv · Answer

asit doesnt say repeating..so
7 *9*8*7*6*5......upto 7th place

mathmath333 · Answer

$\large\tt \begin{align} \color{black}{\text{seven digit numbers:} \ ~\ 

\text{1000000  to 9999999}\~\

\text{counting value is 9000000}\~\
\text{seven digit numbers leading with 5 and 6:}\~\
\text{5000000 to 5999999 and 6000000 to 6999999}\~\
\text{=5000000 to 6999999}\~\
\text{there counting value is 2000000}\~\

{therefore~~ 9000000-2000000=\color{green}{7000000}
}}\end{align}$

mathstudent55 · Answer

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