Sum of the first and last digit of a number in PL/SQL

Prerequisite – PL/SQL introduction
In PL/SQL code groups of commands are arranged within a block. A block group related declarations or statements. In declare part, we declare variables and between begin and end part, we perform the operations.

Given a number n, the task is to find the sum of its first and last digit.
Examples:

Input: 14598.
Output: Sum of the first and last digit is 9.

Input: 987456.
Output: Sum of the first and last digit is 15.

Approach is to use the substr() function and store the first and last digit and then print their sum.

Below is the required implementation:

DECLARE
    -- declare variables are A, B,  C and S
    -- these are same datatype integer
    a INTEGER := 14598;
    b INTEGER := 0;
    C INTEGER := 0;
    s INTEGER;
BEGIN
    IF a > 9 THEN
      c := Substr(a, 1, 1);

      b := Substr(a, Length(a), 1);

      s := b + c;
    ELSE
      s := a;
    END IF;

    dbms_output.Put_line('Sum of the first and last digit is '
                         ||s);
END;
-- Program End

Output:

Sum of the first and last digit is 9