There are number cards from 1 to 9. If you make a 3-digit natural number by picking it by allowing duplicates, find how many possible numbers there are.
1 9 1 [OP_LIST_ARANGE] 3 [OP_LIST_GET_PRODUCT] [OP_LIST_LEN]
var_a = 1
var_b = 9
var_c = 1
list_a = [i for i in range(var_a, var_b + 1, var_c)]
var_d = 3
list_b = [str(i) for i in list_a]
list_b = list(itertools.product(list_b, repeat=var_d))
list_b = [''.join(num_list) for num_list in list_b]
list_b = [str_num for str_num in list_b if str_num[0] != '0']
list_b = [float(i) for i in list_b]
var_e = len(list_b)
print(int(var_e))