You can write formulas like this:
if left({table.account},4) in ["5082" to "5085"] then
"Network Access Services" else
if left({table.account},4} = "5001" then
"Local Service Revenue" else //etc.
It becomes trickier if you have to consider the decimals. You then might want to wrap the string in val() so that the ranges are interpreted correctly.
-LB