An instance of this puzzle is here: https://www.theguardian.com/science/2020/nov/16/can-you-solve-it-the-srcmalbed-nmebur-plzuze
a) It has been swhon taht to raed a txet the oedrr in wihch the lrtetes of ecah idniadiuvl wrod aepapr is not ipmotanrt, so lnog as the fsrit and lsat ltetres are the crorect oens. Tihs is not the csae wtih nmuebrs baecsue if one slcarbmes the ditgis of a nmbeur it is not psisolbe to wrok out waht the ogirianl nemubr was.
Tehre are, hevoewr, cirtaen cesas in wchih tehre is sifuficnet inmoartfion to fnid out the onriiagl neumbrs if olny the interior diigts of ecah of them wree mxied wlihe the fsirt and lstt digtis wree lfet untaelred. Scuh is the csee in the fonlwloig aditiodn:
Can you rseotre the oigrianl atdiiodn and its sum?
(Hint: That lonely red 2 [marked by brackets] is where it should be.)
b) Without the hint of the lonely red 2, there are 13 solutions to the above puzzle. Can a similar puzzle, with a unique solution, be devised, with four five-digit summands, one six-digit sum, and preferably no number with interior digits repeated?