what is the difference between the largest number and the least number written with the digits 9 , 2 , 1 , 5 ?
"explanation : 1259 9521 - - - - - - - - - - - - 8262 answer : d"
subtract(add(add(add(multiply(multiply(9, const_100), const_10), multiply(5, const_100)), multiply(2, const_10)), 1), add(add(add(const_1000, multiply(2, const_100)), multiply(5, const_10)), 9))