This question is taken from the Singapore Mathematical Olmpiad training notes for Primary school. 

Find the middle number in the $29$th row of the [Pascal's triangle](https://en.wikipedia.org/wiki/Pascal%27s_triangle). 

For example, the middle number in $3$rd row is $2$, $5$th row is $6$, $7$th row is $20$, etc. 

What technique can a primary student used to answer this question?