The operation codes 51 - 54 did DECIMAL arithmetic Add , Subtract , Multiply and Divide on the ( variable length ) numbers , one end of each of which was stored at the '' A '' and '' B '' addresses of the instruction .
The operation codes 51 - 54 did DECIMAL arithmetic Add , Subtract , Multiply and Divide on variable length numbers , stored as decimal characters . 
 One end of each operand was stored at the '' A '' and '' B '' addresses of the instruction .