2abcd+abcd7=33581........=> 2abcd+
abcd7
----------
33581........=>
d+7=11 =>d=11-7 => d=4
daca ....d=4 ..=> c=8-4-1 => c=3
=> ...... b=5-3...=>b=2......si ...a= 3-2 => a=1
1a*1000+2b*100+3c*10+4d*1=1234
=>abcd=1234
2abcd=>21234
abcd7=>12347
2abcd+abcd7=33581
21234+12347=33581