If the blood test shows you are iron deficient, and over 65 yrs old, what is the recommended amount of iron that needs to be taken per day?

Find the cause. You're a middle-aged man and if you're iron-deficient, you've got a bleeding ulcer or cancer until proved otherwise, unless it's the result of ill-advised vegetarianism or overzealous blood donation. The exact amount you take for replacement depends more on how much you can tolerate than any specific formula.