Subtraction of Decimals quiz online. Test your math skills on subtracting two decimals with this interactive online quiz. In some cases students will have to borrow before subtracting and in some cases not. Apply subtraction skills learned in previous grades while paying attention to the differences when dealing with decimals. This quiz will give you instant feedback and there is more practice under the worksheets section; hence parents and teachers will find this a useful review resource. This subtracting decimal numbers is a math skill for students in 3rd, 4th, 5th and 6th grade students. Have fun reviewing.