485,635 - 231,957 = 253,678
explanation: the 5 in 485,635 turns into 15 because you cant do 5-7 so, 15-7=8...
the 3 turns into 2 because the 5 turned into 15 on last number. Then the 2 turns into 12 because you cannot do 2-5 but you can do 12-5=7...
the 6 turns into 5 because you turned 2 into 12 on the last number then the 5 turns into 15 because you cant do 5-9 but you can do 15-9=6...
the 5 turns into 4 because you turned 5 into 15 on the last number...
You can do 4-1= 3
you can do 8-3= 5
you can do 4-2= 2