You or someone asked this question yesterday. See
http://www.jiskha.com/display.cgi?id=1224378615
"No repetition" means the same number seven digit does not appear more than once. It does not mean you cannot use the same digit twice; obviously you have to because you have to create a seven digit number with 4 digits.
how many seven digit numbers can be formed with the digits 1,2,4,7 if NO repetition is allowed
1 answer