Suppose that the format for license plates in a certain state is two letters followed by four numbers.

Question

How many different plates can be made if repetitions of numbers and letters are allowed except that no plate can have four zeros?

Answer 1

with no restriction at all : 26x26x10x10x10x10 = 6760000

but there are 26x26 plates that would end in 0000

so number of plates as required above = 6760000-676 = 6759324