Power Query: If x number is between x and y then "Delete" else "Keep"

Hi all,

I have a list of flight numbers and I want to exclude some flight numbers if they are within a specified range.  How would I go about this in power query? 

For example, I have a large data set of individual flights and I want to link the dataset to the reference table of flights to keep/delete, for an easy example, flight numbers:

1 to 500 keep

501 to 600 delete

601 to 1000 keep

so flight number 53 would be kept but flight number 598 would be deleted.  Thanks,

dan80