how many positive integers less than 600 can be formed using the numbers 1 , 2 , 3 , 5 and 6 for the digits ?
"notice that we can find the number of 2 and 3 digit numbers by just assuming the first digit can also be zero : 0 1 1 1 2 2 2 3 3 3 5 5 5 6 6 number of possibilities = 5 * 5 * 5 = 125 . then , just add up the number of 1 digits numbers = 5 , so total is 125 + 5 = 130 . answer : b"
subtract(subtract(subtract(600, 1), const_4), const_1)