why does matrix multiplication in mathematica not produce one single product matrix [duplicate]

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How can I get one single product matrix? Please help! marked as duplicate by Carl Woll, Henrik Schumacher, Jason B., m_goldberg, anderstoodFeb 27 '18 at 1:54

• The trouble is that MatrixForm is only for visualizing the results. Saying c1 = List[{2, 9}, {7, 1}, {7, 8}] is very different than saying c1 = List[{2, 9}, {7, 1}, {7, 8}] // MatrixForm. To fix the issue, don't use MatrixForm when making assignments, only use it for displaying results. – Jason B. Feb 26 '18 at 22:23
• So if I want to multiply C1 and D1, what command should I use? – Aly S. Feb 26 '18 at 22:25
• c1 = List[{2, 9}, {7, 1}, {7, 8}]; d1 = List[{4, 0, 9}, {1, 4, 5}]; result = d1.c1; (* now use MatrixForm to print the result *) MatrixForm @ result – Jason B. Feb 26 '18 at 22:27
• I typed in the exact same thing, and still got the two matrices. Why is that? Thank you so much Jason! – Aly S. Feb 26 '18 at 22:33