Rock climbing on Mars

Sam the rock climber can climb his favorite route at the gym 20 times before he runs out of energy. Approximately how many times would he be able to climb the same route if it were built on Mars?

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Details and Assumptions:

• The radius of Mars is 53% the radius of Earth.
• The mass of Mars is 11% the mass of Earth.
• When climbing on Mars, he has an air supply with the same composition as the Earth's air.