sir you told that mass is the mesurement of inertia.how?

Quantitatively, inertia of a body is measured by the magnitude of force required to change the state of the body. Larger the force required for it, greater is the inertia of the body. We know that for a heavy body, the force required to change its state is large. So, inertia of the body is also large. And for a lighter body, the force required is smaller, so inertia is also smaller.

For e.g.: It is easier to push a motor cycle than to push a truck. The truck being heavier than motor cycle, its inertia is large.

Hence, we conclude that mass is a measure of inertia.