SQL & PL/SQL :: Extract Numbers From Text / Multiply / Get Result

Have 2 small tasks for regexp..where we need to extract numbers from the text & multiply & get the result.

Input field varchar2 : 5x a day x 10 days
Output : 5 * 10 = 50
Select regexp_replace('5x a day x 10 days', '[^[:digit:]]' from dual;

The code extracts numbers ..but doesn't multiply & give the result.Have one more scenario as well.

Input field varchar2 : take 2 tablets (800 mg) by oral route every 4 hours while awake for 10 days
Output : 2 * 800 * 4 * 6 * 10 = 384000
Select regexp_replace('take 2 tablets (800 mg) by oral route every 4 hours while awake for 10 days', '[^[:digit:]]' from dual;

For the above code, if it's hours ..we need to convert into day by multiplying with the required factor to make it a day.