Question

va roooogg 12
vaaa rooooggg dau coroanaaa ​

Answer 1

$\it Fie\ n\ un\ astfel\ de \ num\breve ar.\\ \\ n:6=c\ \ rest\ 4 \Rightarrow n= 6c+4\\ \\ n\ este\ format\ din\ dou\breve a\ cifre \Rightarrow n\ poate\ fi:\\ \\ 6\cdot1+4\\ \\ 6\cdot2+4\\ \\ 6\cdot3+4\\ .\\.\\.\\6\cdot15+4\\ \\ Suma \ este:\\ \\ S=6\cdot(1+2+3+\ ...\ +15)+15\cdot4=6\cdot\dfrac{15\cdot16}{2}+60=720+60=780$