Lets assume if you want to check whether any of the columns 2,3,4 or all the columns have been updated or not. Then use the following IF condition

IF (COLUMNS_UPDATED() & 14) > 0

14 is the bitmask for all three columns.

for col 2, (this is col id you can see in syscolumns table) bitmask is power(2,(2-1))=2

for col 3, bitmask is power(2,(3-1))=4

for col 4, bitmask is power(2,(4-1))=8

In above ex, since your checking all there columns bitmask is the sum of all. That comes to 14.