How to divide two columns in one table and update the third column in sqlite?

My table has six columns.

`Master       Class    SubClass    Sum1    Sum2    Division
 Stationary   Pencil     HB        1000    500     (1000 / 500)
 Stationary   Pencil     H1        500     400     (500 / 400)
 Boxes        Hard Box   Black      20      10      (20/10)
 BOxes        Card Boxes White      40      20      (40 / 20)

How to get this division and update Division Column?