(defn to-celsius [k]
  (- k 273.15))
(defn to-fahrenheit [k] 
  (- (* k 1.8) 459.67))
(defn to-rankine [k] 
  (* k 1.8))

(defn temperature-conversion [k] 
  (if (number? k) 
    (format "Celsius:%.2f Fahrenheit:%.2f Rankine:%.2f" 
      (to-celsius k) (to-fahrenheit k) (to-rankine k)) 
    (format "Error: Non-numeric value entered.")))