Are there other numbers on the report? If not, here's what I recommend.
-Sort your data descending by number. This will put no 53 ahead of no 48.
-Create a formula called "Has53" that looks something like this (use the correct table and field for your data):
BooleanVar Has53;
if previousIsNull({table.department}) or
({table.department} <> previous({table.department}) then Has53 := false;
if {table.number} = "no 53" then Has53 := true
else Has53 := Has53;
Has53
-On the section where you're displaying your data, add something like the following suppression formula:
-Dell