If

111 + 168 = 2001
211 + 606 = 1201
521 + 926 = 1501
889 + 816 = 9091
169 + 898 = 6551
869 + 168 = 6851
251 + 696 = 1211
951 + 998 = 2201
651 + 268 = 1501
191 + 598 = 9201
291 + 998 = 8201

Then

105 + 509 + 588 = ?

• Do not think too far, this strange math have a very simple rule. – Jamal Senjaya Sep 26 '16 at 9:00

• So $885+605+501=1991$ and the answer is $1661$. Why 5 and 2 are not respectively swapped turning upside down? – z100 Sep 26 '16 at 9:22