Question

Calculati suma resturilor posibile ale impartirii unui nr nat la 9

Answer 1

$Resturile~pot~fi:~0,1,2,3,4,5,6,7,8. \\ \\ S=0+1+2+3+...+8= \\ \\ ~~~= \frac{8(8+1)}{2}= \\ \\ ~~~=4 \cdot 9= \\ \\ ~~~=36.$

Answer 2

Resturile posibile impartirii unui numar la 9=0,1,2,3,4,5,6,7,8
suma resturilor=0+1+2+.............+8
0 la adunare=0 deci
suma resturilor=1+2+............+8=8x(8+1):2=8x9:2=72:2=36