$\sum_{i=1}^{∞}\sum_{j=1}^{∞}a_{ij}=\sum_{j=1}^{∞}\sum_{i=1}^{∞}a_{ij}=\text{lim}_{r\to∞}\sum_{(i,j)\in rV}a_{ij}$

Question

Let $a_{ij} ∈ \mathbb{C}$, $i, j = 1, 2, . . $ . If $\sum_{i=1}^{∞}\sum_{j=1}^{∞}|a_{ij}|<∞$

Then

$\sum_{i=1}^{∞}\sum_{j=1}^{∞}a_{ij}=\sum_{j=1}^{∞}\sum_{i=1}^{∞}a_{ij}=\text{lim}_{r\to∞}\sum_{(i,j)\in rV}a_{ij}$.

Where $V$ is any neighborhood in $(0,0)$ in $\mathbb{R}$ and $rV := \{rx : x ∈ V \}$.

Any suggestions please.