a) 2,(3) = (23-2)/9 = 21/9 = 7/3
1,5 = 15/10 = 3/2
7/3 • 3/2 = 7/2 = 3,5
b) 4,(6) = (46-4)/9 = 42/9 = 14/3
0,1(3) = (13-1)/90 = 12/90 = 2/15
14/3 • 2/15 = 28/45 = 0,6(2)
c) 4,(5) = (45-4)/9 = 41/9
2,(1) = (21-2)/9 = 19/9
41/9 • 19/9 = 779/81 = 9,(617283950)