Need to block ?

[Bob Goodwin - W2BOD <bobgoodwin wildblue net>]

What is the correct notation for blocking a range of addresses in my router?

If I block 64.18.5.13  it simply moves up to 64.18.5.14.

I thought the proper way to do it was 64.18.5.0/255 but obviously that's 
wrong or at least doesn't work for me.

Whatever it is has run my upload data allotment up to 3gigs and I'm only 
allowed 5g for 30 days!  So this is a panic and I haven't been able to 
find why this is possible?

Bob Goodwin