Answer
$2.6\times10^{9}$ times in a life time.
Work Step by Step
A normal heart rate is about 70 beats/min.
A person lives for about 70 years,
Now, $ 1 yr = 5.26\times 10^{5} min$
So, the heart beats about $70 \times 70\times 5.26\times 10^{5} =2.6\times10^{9}$ times in a life time.
