In terms of matrix
representation, we can write the above information as follows:
Requirements
Prices per piece (in Rupees) Money needed (in Rupees)
2
5
8
10






5
50





5
2
5 50
260
8 5
10
50
540
×
+
×




=




×
+
×




Suppose that they enquire about the rates from another shop, quoted as follows:
pen – ` 4 each,  story book – ` 40 each Now, the money required by Meera and Nadeem to make purchases will be
respectively ` (4 × 2 + 40 × 5) = ` 208 and ` (8 × 4 + 10 × 40) = ` 432
Rationalised 2023-24
MATRICES         51
Again, the above information can be represented as follows:
Requirements
Prices per piece (in Rupees) Money needed (in Rupees)
2
5
8
10






404





4
2
40 5
208
8 4
10 4 0
432
×
+
×




=




×
+
×




Now, the information in both the cases can be combined and expressed in terms of
matrices as follows:
Requirements
Prices per piece (in Rupees)
Money needed (in Rupees)
2
5
8
10






5
4
50
40






5
2
5 50
4
2
40 5
8 5
10 5 0 8 4
10 4 0
×
+ ×
×
+
×




×
+
×
×
+
×


= 
260
208
540
432






The above is an example of multiplication of matrices We observe that, for
multiplication of two matrices A and B, the number of columns in A should be equal to
the number of rows in B Furthermore for getting the elements of the product matrix,
we take rows of A and columns of B, multiply them element-wise and take the sum