DAX calculated column that sums by another column

Hello friends,

I have this table and I need to calculate the result in column TotalForProduct, which sums all the amounts per each Product:

Product | Month | Amt | TotalForProduct

A           | Jan       | 100 | 300

A           | Feb       | 200 | 300

B           | Jan       | 100 | 200

B           | Feb       | 100 | 200

How do I calculate this last column? I have it to be a column, not a measure. And it has to be DAX, not Power Query.

Thank you,

Michael