IshanGre wrote:

I solved this question by multiplying 45 and 89 and hence got 4005- which has 0 as tenth and 5 as unit digit which is equal to 0 hence A.

How do we know that taking just the last 2 digits of each number can give us a reliably correct corresponding units and tens digit for the whole numbers multiplied? Can someone clarify if this is a mathematical property being used?

I used the traditional matrix method for multiplying the two numbers, BUT JUST FOR LAST 2 DIGITS and ignoring the rest.

12345

x6789

______

x x x x 5

x x x 0 0

x x 5 0 0

x 0 0 0 0

__________

x 0 5 0 5