Yes.
There should be no points after the decimal point.
87.656 87.66
Decimal points aren't positive or negative. Decimals can be either.
It is like that because multiplying any number by 10 is the same as adding a 0 at the end of it, unless it is a decimal number. But decimal numbers are not multiples of 10.
Put the numbers in a column with the decimal points aligned. Add the numbers ignoring the decimal points. Insert the decimal point in the answer exactly below the column of decimal points in the numbers being added (summands).
A number with two decimal points cannot be a decimal number.
Write the numbers in a column so that all the decimal points are one below the other. Put a decimal point in the answers underneath the coumn of decimal points. Then add the numbers ignoring the decimal points.
Unlike addition, there is no need to line up the decimal points. Just multiply ignoring the decimal points. When you are done, move the decimal point of the result to the left equal to the number of digits after the decimal point for both multiplicands.
decimal, metric system
A decimal number can't have two decimal points in it
When adding decimal numbers, the decimal points should be lined-up.
A number cannot have 3 "decimal" points in it.