iterating over multiple variables with \foreach it TikZ

Question

Note: I'm aware of another response here, but its solution was a quick-fix rather than the underlying issue.

Say I want to create the following diagram but using iteration:

\begin{tikzpicture}
\foreach \x/\y in {1/10,2/11,3/12,4/13,5/14,6/15}
 {
    \draw (\x,0) circle (7pt);
    \draw (\x,0) node {$\y$};
 }
\end{tikzpicture}

I could easily exploit the fact that tikz chooses an appropiate center so that

\begin{tikzpicture}
\foreach \x in {10,11,...,15}
 {
    \draw (\x,0) circle (7pt);
    \draw (\x,0) node {$\x$}; 
 }
\end{tikzpicture}

works just as well. But if I don't want to use this exploit, and try

\begin{tikzpicture}
\foreach \x/\y in {1/10,2/11,...,6/15}
 {
    \draw (\x,0) circle (7pt);
    \draw (\x,0) node {$\y$};
 }  
\end{tikzpicture}

I get a bunch of errors, beginning with

Illegal unit of measure (pt inserted). [ }]

Two questions: it is possible to iterate over several variables in a list (let's assume the lists are large enough that it's not feasible to do each of the cases by hand as above), and what's causing the error?

Thanks