a=2...(2000)
b=5...(500)
c=3...(30)
d=3....(3)
2533+533+33+3=
=3066+36
=3102
......................................................................................................
a*1000+2b*100+3c*10+4d=3102
3c*10+4d=102...=> 3c=102-3*4....=3c=102-12....=>3c=90...=>c=30
3c*30+4d=102...=> 4d=102-90.....=>4d=12....=>d=12:4....=>d=4
a=3000-1000
a=2000
b=(3000-2000):2
b=1000:2
b=500
1*2000+2*500+3*30+4*3=
=2000+1000+90+12
=3000+102
=3102
=> abcd=2000+500+30+3
=2533
bcd = 500+30+3
=533
cd =30+3
=33
d=3
2533+533+33+3=3102