The product of the digits of 3214 is 24. How many distinct four-digit positive integers are there such that the product of their digits equals 18?
1129 1136 1163 1192 1219 1233 1291 1316 1323 1332 1361 1613 1631 1912 1921 2119 2133 2191 2313 2331 2911 3116 3123 3132 3161 3213 3231 3312 3321 3611 6113 6131 6311 9112 9121 9211 Total = 36 such numbers.
"Distinct 4-digit numbers". I think you only have: 1129, 1136, 1233. The other 33 listed above are simply "permutations" on these 3 "distinct combinations".
