There are several standard exercises which train students to convert percentages, decimals and fractions. Converting percentage to decimals for example is actually as simple as moving the decimal point two places to the left and losing the percent sign "%." Thus 89% is equal to 0.89. Expressed in fraction, that would be 89/100. When you drill kids to do this often enough, they learn to do conversion almost instinctively.
Point is, whatever it takes to get students actively involved with the reviewing process where they are not bored and effectively reviewing grade level material in order to prepare them for state or quarterly assessments.
Save Time : Free worksheets not only save you money, they can also save you time. If you decide that it is best for your child to do worksheets especially tailored for his needs, by doing a little research for printable math worksheets found online, you don't have to make the worksheets yourself. This can save a lot of time. Worksheets aren't that difficult to make, but it can be time consuming.
Worksheets also, when used properly, provide both the students and parent / tutor immediate feedback as to the child's progress. This means they can be used to point out areas where the student needs further reinforcement.