A billion beats

Nobody can count every beat of a heart, but anybody can estimate. A resting heart beats about seventy times a minute. This is an example: it differs from person to person and from animal to animal.

Estimating the beats of a heart. At rest, $r=70$ a minute (an example).

$N=r\times t$, with $r=70$ (example).

Seventy a minute, sixty minutes an hour, twenty-four hours a day: that is about a hundred thousand beats every day. To be exact, a hundred thousand and eight hundred.

In a day: $70\times 60\times 24=100800\approx 10^5$.

$70\times 60\times 24=100800\approx 10^5$.

Now multiply by the three hundred and sixty-five days of a year and by eighty years. The answer is about three billion beats in a lifetime.

In $80$ years: $N=100800\times 365\times 80\approx 2.9\times 10^9$, about three billion.

$N\approx 2.9\times 10^9$ in $80$ years.

Try a mouse: a heart at six hundred beats a minute and a life of two years gives about six hundred and thirty million. An elephant, thirty a minute and sixty years, gives about nine hundred and fifty million. These are rough figures, taken as examples.

Mouse: $600\times 60\times 24\times 365\times 2\approx 6.3\times 10^8$. Elephant: $30\times 60\times 24\times 365\times 60\approx 9.5\times 10^8$.

Mouse $N\approx 6.3\times 10^8$, elephant $N\approx 9.5\times 10^8$.

The surprise: lives of two, sixty and eighty years, yet between six hundred million and three billion beats. A quicker heart goes with a shorter life. Three numbers cannot tell us why, so estimate, but do not make promises.

Lives of $2$, $60$ and $80$ years, yet $N$ from $6\times 10^8$ to $3\times 10^9$. Quicker heart, shorter life; only an estimate.

$6\times 10^8\le N\le 3\times 10^9$.