Matrix A is multiplied by matrix B to get matrix C, the method is that the first row of A is multiplied by the first column of B, and the addition is C11. The first row of A corresponds to the second row of B. If the elements are added together to get C12, and so on, the second row of C is the second row of A and the second row of A is multiplied by B according to the above method, and so on. N-order matrices are multiplied in this way, the number of columns in A must be equal to the number of rows in B.

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