Question

Dau coronita!!
Calculand S=4+5+6+7+...+100, vei obtine:
Trebuie sa dea 5044.

Answer 1

S=4+5+6+7+...+100
observam ca lipseste 1+2+3
1+2+3=3*(3+1)/2=1,5*4=6
acum putem calula S
S=4+5+6+7+......+100=100*(100+1)/2-6=50*101-6=5050-6=5044

Answer 2

S=(1+2+3+4+5+6+...+100)-(1+2+3)=(100*101)/2-6=50*101-6=5044-adevarat.