[tex]1. \\
a)0,6*0,9= \frac{6}{10}* \frac{9}{10}=0,54 \\ \\
b)2,5*6= \frac{25}{10}*6=15 \\ \\
c)6,05*0,4= \frac{605}{10}* \frac{4}{10}=24,2 \\ \\
2. \\
1s.......50,4~kg \\
5s.......50,4~kg*5=252~kg \\
10s.....50,4~kg*10=504~kg \\ \\
3. \\
a)25,4*6,8= \frac{254}{10}* \frac{68}{10}=172,72 \\ \\
b)125*0,2= 125*\frac{2}{10}=25 \\ \\
c)611*0,06=611* \frac{6}{100}=36,66 [/tex]