Correct

那当儿

/ nā dāngr / 
Strokes

Example

As an Adverb

at that time; in those days

1
Nā
那
dāngr  
当儿
  
,
wǒ
我
cái
才
  
5
suì
岁
  
。

It was when I was only five.

2
Nā
那
dāngr  
当儿
  
,
wǒ
我
juéde
觉得
shìjiè
世界
de
的
mòrì
末日
láilín
来临
le
了
  
。

At that time, I thought it was the end of the world.