using google customsearch can you sort by metatag as a number

Question

I am doing a Google customsearch function in an angularjs application calling search results using ajax

I can sort the data, but it is treating the metatag values I'm using as a string rather than the number(integer) that it should be.

data['sort']=' more:pagemap:metatags-featuredindex';

here is an example of the meta tag

is there any way to make it treat it as an integer? the docs are confusing and mostly talk about dates.