How many balloons does it take to lift this?

Question

a 120 pound person

and an around 15 pound lawn chair.

Answer 1

In July 1982 a truck driver with 42 six-foot weather balloons rigged to a lawn chair took a 45-minute ride aloft to 16,000 feet today before he got cold, shot some balloons out and crashed into a power line, the police said.

Read the link below for more details.

The Discovery channel show MythBusters re-enacted the same activity a couple seasons ago.

If you're going to try it, bring a parachute and a BB gun.

Answer 2

One big balloon with more than 135 pounds of lift, or 135 small balloons with over 1 pound of lift each.

There are also many answers in-between.