2 x ( 1 / 5 ) = 2 / 5 ⇒ sau 1 /5 + 1/ 5 = 2 / 5
2 x ( 2 / 5 ) = 4 / 5 sau 2 / 5 + 2 / 5 = 4 / 5
(4 / 10 ) : 2 = 4 / 10 × 1 / 2 = 4 / 20 = 1 / 5 → jumatatea lui 4 /10
( 6 / 8 ) : 2 = ( 6 / 8 ) × 1 / 2 = 6 / ( 8 × 2 ) = 6 / 16 = 3 / 8 → jumatatea lui 6/8