Decimal Number Illustrated Quiz Online. This is an interactive exercise introducing the concept of decimals through pictures. Each problem contains pictures similar to those that seen in the section under fractions. A way of doing it easily is to first convert as a fraction and then reduce the fraction to a decimal. This exercise is a mcq; hence after solving each problem, select the correct answer and submit. Get more practice by printing out worksheets on decimals from this site. This is a decimals quiz for for 3rd, 4th, 5th and 6th grade students.