1). Count the total number of decimal places AFTER the decimal points
in both numbers. In your example, there's one in the 2.4 and one in the 3.5,
for a total of two. Put that '2' in your pocket for later.
2). Now forget about the decimal points. Just write the numbers
one under the other, and multiply them as usual.
like 24
x 35
3). When you get the answer (like 840), THEN pull out the '2' that you have been
saving in your pocket from before.
Starting at the RIGHT side of your answer, count '2' places back from the end
and put a decimal point there.
Now you have ' 8.40 '.
That's the answer to multiplying the decimals.
