Help to use Calc

[jojojojojoj5564656465465]

import { calc } from '@vanilla-extract/css-utils'

const nbCards = createVar({
  syntax: '<integer>',
  initialValue: '10',
  inherits: false,
})

inlineSize: calc.divide('60rem', nbCards), 

Why it's not working ?

inlineSize: calc.divide('60rem', '10' ), <=== it's working this way