1800mg. You probably should not exceed 1800mg a day. This all depends on your age, weight, renal function, and any comorbid medical conditions you might have. There is no one right number.
6 of the 200mg. Officially - here ya go : max: 6 tabs or caps/24h; info: use lowest effective dose, shortest duration; - although as a prescription medication = we occasionally prescribe 800mg 2-3 times a day for a short period of time if there a re no ulcer / bleeding contradindications.
3200 mg. For healthy adults 800 mg four times a day( every 6 hours) is the maximum, but ulcers, bleeding, upset stomach, injury to the kidneys, increase in blood pressure, worsening of leg edemas may happen with much lower dosis. Protect your stomach with Prilosec or Zantac (ranitidine) or Pepcid and antacids. Take them with food.