# How to find the sum $\sum_{k=0}^{n}\binom{n+k}{k}$?

How to find the sum $\displaystyle\sum_{k=0}^{n}\dbinom{n+k}{k}$?

In my book it is written as a hint that we can use the formula $\dbinom{n}{r}+\dbinom{n}{r-1}=\dbinom{n+1}{r}$ to find it.But I can't figure out how to apply it here.Any ideas?

Here's a hint to get started. It helps to note that anything choose $0$ is equal to $1$.
\begin{align} \sum_{k=0}^n\binom{n+k}{k}&=\binom{n}{0}+\binom{n+1}{1}+\sum_{k=2}^n\binom{n+k}{k}\\ &=\binom{n+1}{0}+\binom{n+1}{1}+\sum_{k=2}^n\binom{n+k}{k}\\ &=\binom{n+2}{1}+\sum_{k=2}^n\binom{n+k}{k} \end{align}