Question

why millions of sperms are produced in male when only one sperm is requiredto fertilize an ovum?

Answer 1

Millions of sperm are produced by males in single ejaculation. But during their passage to female tract, some of the sperms get damaged and are unable to reach the fallopian tube. There is a competition between different sperms for fertilizations. So the most superior sperm will fertilise the ovum and rest will be destroyed in their path.