Question

1+2+3+....73=
Repede va rog 

Answer 1

1+2+3+    .........................+73=
73+72+.............................+1=
-----------------------------------------------------
74+74+...............................+74
nr. de termeni   73-1+1=73
73x74=5402
2S=5402
1s=2701

Answer 2

Formula lui Gaus

$\frac{n(n+1)}{2} \\ n=ultimul/numar \\ \\ \frac{73(73+1)}{2} = \frac{73*74}{2} = \frac{5402}{2}=2701$