Harvey wrote
BTW not sure how you did your math, but I am OLD (59) and get paid weekly. Hope to retire at 65.
Whoops! My bad. Was thinking in terms of monthly.
For 6 years, $70 per week, same assumptions (your investment earning 10% per year), you'll have about $30k more.
Excel does the math for you (assuming you put in the correct numbers!) with the FV function.
In your case FV (future value) = (.01/52, 6*52, -70,0) = $29,886.92.