Away:Script-planck

;; set precision to 50
&::echo(50);>&conf_math_scale

;; speed of light
&::echo(299792458);>&c

;; gravitational constant
math::pow(10 -11);>>
math::mul(6.67430 <<);>&G

;; 2pi
math::pi();>&pi
math::mul(<&pi 2);>>

;; reduced planck constant
math::pow(10 -34);>>
math::mul(6.62607015 <<);>>
math::div(<< <<);>&h_bar

;; planck length
math::mul(<&h_bar <&G);>>
math::pow(<&c 3);>>
math::div(<< <<);>>
math::sqrt(<<);>&l_P

;; kilometre -> l_P
math::mul(1 1000);>>
math::div(<< <&l_P);>>

&::echo(1 km = << l_P);