storage space

good day!

i have the ff: table structures:

 Table "quantities"
 Attribute |     Type      | Modifier
-----------+---------------+----------
 invnbr    | varchar(12)   |
 ordernbr  | varchar(12)   |
 prodid    | varchar(30)   |
 invqty    | numeric(12,2) |
 uprice    | numeric(12,2) |

 Table "notes"
 Attribute |     Type      | Modifier
-----------+---------------+----------
 ordernbr  | varchar(12)   |
 line1  | varchar(60)   |
 line2  | varchar(60)   |
 line3  | varchar(60)   |

with the above structures, is it advisable to separate "notes" table from "quantities" to save storage space because an invoice to us may or may not have note/s?

thanks,
don