$1,25\cdot 2,75=1\frac{1}{4}\cdot 2\frac{3}{4}=\frac{5}{4}\cdot \frac{11}{4}=\frac{55}{16}=3\frac{7}{16}=3\frac{35}{80}=3\frac{35\cdot 125}{80\cdot 125}=3\frac{4375}{10000}=3,4375\approx 3,44\text{zł}$