What i want is, when i key in the month in B1, the values in B2 to B7 should be filled up automatically as shown in the file.

1 to 30 - One month before Current Period
31 to 60 - Two months before Current Period
61 to 90 - Three months before Current Period
91 to 180 - Four to Six months before Current Period
181 to 360 - Seven to Twelve months before Current Period
361 Above - Thirteen months & Before