a)
2,5=25/10=5/2
3,25=325/100=13/4
5/2 : 13/4 = 5/2 • 4/13 = 10/13
b) 0,3=3/10
0,(3)=3/9=1/3
3/10 : 1/3 = 3/10 • 3 = 9/10
c) 0,2(6)=(26-2)/90=24/90=4/15
2,(8)=2 intregi 8/9=26/9
4/15 : 26/9 = 4/15 • 9/26 = 6/65
d) 1,25=125/100=5/4
2,1(3)=2 intregi (13-1)/90=2 intregi 12/90=2 intregi 2/15=32/15
5/4 : 32/15 = 5/4 • 15/32 = 75/128
