In this short code snippet I try to get maximum number of a variable typed as packed number and compare it against given amount.

This code can be used to detect possible overflow and let program react accordingly.

CLASS lcl_amount_checks DEFINITION.
  PUBLIC SECTION.
    CLASS-METHODS:
      check_max_amount
        IMPORTING  iv_pack_length   TYPE i DEFAULT 7
                   iv_pack_decimals TYPE i DEFAULT 2
                   iv_amount        TYPE p
        EXCEPTIONS amount_too_big.
ENDCLASS.

CLASS lcl_amount_checks IMPLEMENTATION.
  METHOD check_max_amount.
    DATA:
      lr_amount TYPE REF TO data.

    CREATE DATA lr_amount 
      TYPE p LENGTH iv_pack_length 
      DECIMALS iv_pack_decimals.
    ASSIGN lr_amount->* TO FIELD-SYMBOL(<lv_amount>).

*   GET MAX amount for P(LENGTH,DECIMALS)
    DATA(lr_max_value) = cl_abap_exceptional_values=>get_max_value( 
                           <lv_amount> ).
    ASSIGN lr_max_value->* TO <lv_amount>.

    IF iv_amount GT <lv_amount>.      
      MESSAGE 'Amount too large' type 'E' RAISING amount_too_big.
    ENDIF.
  ENDMETHOD.
ENDCLASS.