5x2m 55cm

5 * ( 2 m 55 cm ) =  5* 2,55 m = 12,55 m  = 12 m 55 cm

$${\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{2.55}} = {\frac{{\mathtt{51}}}{{\mathtt{4}}}} = {\mathtt{12.75}}$$

Gruß radix !