- Count how many spaces there are after the decimal point in each number.
- Locate the number which has the most digits on top
- Multiply as if the point didn't exist.
- Locate the decimal point depending on how many spaces you had in each number.
3.12 X 4.2
- The first number has 2 spaces
- The second number has only one space
- There are 3 spaces in total
The answer is 13.104
Remember that a point is different from a coma.