Expert: Josh - 4/7/2007

Question
Please help me if you can my son brought this question home for homework and I don'know how to figure it out. Explain how an array of 5 x 46 can help you find the product of 5 x 46.
Thank you,
Connie

Answer
Connie,

An example is needed to verify the meaning of an array.

If this is about building a multiplication table, and the meaning of a 5-by-46 array is [1,2,3,4,5]' * [1,2,3,...,46], the entry in row i and column j corresponds to i times j.
e.g., the entry in row 3 and column 12 corresponds to 3*12=36.

Since multiplication is commutative, i*j is same as j*i.
Finding 46 x 5 is equivalent to finding 5 x 46.

To find the product of 5 times 46, we can find the entry in row 5 and column 46. The value of that entry should be 230 -- the product of 5 and 46.