Question

3+6+9+12+....+2019
Calculati

Answer 1

3+6+9+12+...+2019=3(1+2+3+4+...+673)=3*673*674/2=3*673*337=680403

Answer 2

Dai termen comun pe 3 si ai :

3(1+2+...+673)=

3(673*674)/2=

=680403