ꕤ Pasul 1 - scriem formula (suma lui Gauss)
[tex]\displaystyle 1+2+3+...+n=\bold{\frac{n\cdot(n+1)}{2}}[/tex]
ꕤ Pasul 2 - aplicăm formula
[tex]\displaystyle 1+2+3+4+...+100=\frac{100\cdot(100+1)}{2}\\ \\ =\frac{\not100\cdot101}{\not2} \\\\ =50\cdot101 \\ \\ = 5050[/tex]