# How does this addition work (13+7=1130)?

I found this problem on 9gag and I have no idea how to solve it.

Here is the question:

$13+7=1130$

$88+9=47$

$32+28=2530$

$10+999=1149$

$444+77=61$

$55+111=56$

$21+0=1221$

$7+22=39$

$33+5=38$

$123+45=???$

The puzzle says to think outside the box.

Here is the image:

• Well, the ones' digits are all correct, so the answer probably ends in 8...
– user88
Jul 12, 2015 at 19:34
• If possible I think it might be wise to source/link where you go this puzzle from if you just copied it. Jul 13, 2015 at 14:45
• Sure, 9gag.com/gag/azVrZRj
– user10001
Jul 13, 2015 at 14:48
• Looking at your latest edit, is the answer supposed to have three digits? Jul 13, 2015 at 14:58
• Not sure if it's relevant, but in the original the 1s and the kerning around them are odd. $21+0=1221$ almost looks like $21+0=\lvert 22 \rvert$ to me. Jul 13, 2015 at 16:25

13 + 7 = one 1 one 3 + one 7 = 1113 + 17 = 1130
88 + 9 = two 8 + one 9 = 28 + 19 = 47
32 + 28 = one 3 one 2 + one 2 one 8 = 1312 + 1218 = 2530
10 + 999 = one 1 one 0 + three 9 = 1110 + 39 = 1149
etc.

So the final solution is

123 + 45 = one 1 one 2 one 3 + one 4 one 5 = 111,213 + 1415 = 112,628

• +1 Nice! The sad thing is, in trying to figure this out last night, I thought of the "look-and-say numbers", as featured in this Numberphile Youtube video featuring John Conway, but I still didn't make the connection!
– JLee
Jul 14, 2015 at 15:03
• Wow... Well this solution just reminded me of another good puzzle I know... probably need to save it for a bit. Jul 14, 2015 at 17:38