Question

3 +6 +9 +12 +.....+123​

Answer 1

SUMA LUI GAUSS

3+6+9+12+....+123=?

3×1+3×2+3×3+3×4+...+3×41=

3×(1+2+3+4+5+....+41)=

3×41×42÷2

123×42÷2=

5166÷2=2583

Answer 2

3+6+9+12+...+123=

=3(1+2+3+4+...+41)=

=3×(41×42)/2=

=3×41×21=

=123×21=2583