Correct

便中

/ biàn zhōng / 
Strokes

Definition

at one's convenience/when it's convenient

Example

As an Adverb

at one's convenience; when it's convenient (to)

1
Biàn
便
zhōng
中
qǐng
请
gàozhī
告知
yú
于
tā
他
  
。

Please inform him of it at your convenience.