Question

how to evaluate this
\[\large \sum\limits_{m,n=1}^3 (mn) = ?\]

Answer 1

3

Answer 2

1*(1+2+3) + 2*(1+2+3) + 3*(1+2+3)
?

Answer 3

\[= \left( \sum\limits_{n=1}^3 n\right)\left( \sum\limits_{m=1}^3 m\right) \]

Answer 4

Nice :) the one i wrote is a short form for that product is it ?

Answer 5

which is the same as @INewton wrote

Answer 6

Oh I see...