Answer
$2,095,681,645,538$
Work Step by Step
By using the fundamental counting rule we can get the number of possibilities:
1 character: $26$.
2 characters: $26\times36=936$.
3 characters: $26\times36\times36=33,936$.
4 characters: $26\times36^{3}=1,213,056$.
5 characters: $26\times36^{4}=43,670,016$.
6 characters: $26\times36^{5}=1,572,120,576$.
7 characters: $26\times36^{6}=5,659,634,0736$.
8 characters: $26\times36^{7}=2,037,468,266,496$
Total:$2,095,681,645,538$.
