Răspuns:
R < I
R=0,1,2,3,4
a:5= c rest r
c=r
a=5r+r=>a=6
a=6·0=0
a=6·1=6
a=6·2=12
a=6·3=18
a=6·4=24
sau
a₁ : 5 = 0 rest 0 =>a₁=0·5+0 = 0
a₂ : 5 = 1 rest 1 =>a₂=1·5+1=6
a₃ : 5 = 2 rest 2 =>a₃=2·5+2=12
a₄ : 5 = 3 rest 3 =>a₄=3·5+3=18
a₅ : 5 = 4 rest 4 =>a₅=4·5+4=24