1+2+3+4...96+97+98+99+100=?

Răspuns :

100 + 1 = 101
  99 + 2 = 101
  98 + 3 = 101

pana la...
  51 + 50 = 101

  50 perechi a cate 101,

101 × 50 = 5050

1 + 2 + 3 + 4 + ........+ 96 + 97 + 98 + 99 + 100 =
100 * (100 + 1) : 2 =
50 * 101 = 
5050