This can be explained by thinking numbers on the number line as:
Lets take we have to multiply a positive number (say, 2) with a negative number say (-3)
<u>2×(-3)</u>
Suppose someone is standing at 0 on the number line and to go to cover -3 , the person moves 3 units in the left hand side. Since, we have to compute for 2×(-3), The person has to cover the same distance twice. At last, he will be standing at -6, which is a negative number.
A image is shown below to represent the same.
<u>Thus, a positive times a negative is a negative number.</u>