Israt()
{{Function:israt(<string>)}}
This function will return 1 (TRUE) if the argument is a rational and 0 (FALSE) otherwise. Rational by this definition includes many real numbers, but excludes scientific notation and 'special words': NaN, -Inf, +Inf, and Ind.
You can test more restrictively with isint() and more inclusively with isnum().
Example
> say israt(22223.0000)
You say "1"
> say israt(+77)
You say "1"
> say israt(1E20)
You say "0"