The math coprocessor is the math specialist. If a CPU is so equipped, all math calculations can go to this part of the CPU. This could relieve some of the processing from the main part of the CPU and make the CPU operate faster.

What's the catch? The specific application software you are running must be designed to use the math coprocessor. Most does not, but math intensive software will.

You can add a math coprocessor to older PCs, but newer CPUs have the math coprocessor built in.