For $2023,$ Compute the additional Medicare tax for the following taxpayers. If required, round your answers to the nearest dollar.

a$.$ Mario, who is single, earns wages of $$340,600.$

His additional Medicare tax is $$\_\_\_\_\_\_$

b$.$ George and Shirley are married and file a joint return. During the year, George earns wages of $$270,200,$ and Shirley earns wages of

$$405,300.$

Their additional Medicare tax is $$\_\_\_\_\_$

c$.$ Simon has net investment income of $$58,280$ and MAGI of $$291,400$ and files as a single taxpayer.

Simon's additional Medicare tax is $$\_\_\_\_\_\_\_$