How many times does a human heart beat in a lifetime?

Question

A resting heart beats a little more than once a second. Assume an average rate of about $70$ beats per minute and a lifespan of roughly $78$ years. Solve in your head.

Estimate the total number of heartbeats in one human lifetime. Aim: under 30 seconds.

Accepted Answer

Build the answer one multiplier at a time, keeping round numbers. - Per hour: 70 	imes 60 = 4{,}200. - Per day: 4{,}200 	imes 24 \approx 100{,}000 (exactly 100{,}800). - Per year: 100{,}000 	imes 365 \approx 3.65 	imes 10^{7}, call it 37 million. - Per life: 37 	imes 10^{6} 	imes 78 \approx 2{,}900 	imes 10^{6} \approx 2.9 	imes 10^{9}. So the estimate is roughly 3 billion beats, comfortably inside a 2.5–3.5 billion range depending on the resting rate you assume. Takeaway. The trick is to round 70 	imes 60 	imes 24 to a clean 100{,}000 beats per day early, that single anchor turns t…

How many times does a human heart beat in a lifetime?

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