Use Fermat's Little Theorem to find the least positive residue of \(6 ^ { 542 }\) modulo 13
Seven students, Alan, Brenda, Charles, Devindra, Enid, Felix and Graham, are attending a concert and will sit in a particular row of 7 seats. Find the number of ways they can be seated if
there are no restrictions where they sit in the row,
Alan, Enid, Felix and Graham sit together,
Brenda sits at one end of the row and Graham sits at the other end of the row,