Cannot pass number variable to \markup.

[dfro]

Hello, fellow music engravers.

I would like to pass a number variable to \markup, but my attempts are 
not working.

When I try to pass a number variable to \markup I get the following message:

"error: syntax error, unexpected NUMBER_IDENTIFIER".

Examples:

<code start> fontsize-number = #5 { c'1^\markup \fontsize 
\fontsize-number "text" }

<code end>

or,

<code start>

raise-number = #5 { c'1^\markup \raise \raise-number "text" }

<code end>

Could someone help me to comprehend how to do this?

Thanks,

David