Intro to Millwright Practice Exam

What must be the same when adding and subtracting fractions?

1. The numerator

2. The denominator

3. The whole number part

4. The decimal value

The correct answer is: The denominator

When adding and subtracting fractions, it is essential that the denominators are the same. This is because the denominator represents the total number of equal parts into which the whole is divided. For fractions to be combined, they must refer to the same-sized pieces; therefore, having a common denominator allows us to properly add or subtract the numerators, which represent the number of those parts. For example, if you have the fractions 1/4 and 1/2, you cannot simply add or subtract them directly because the denominators (4 and 2) are different. Before performing the operation, you need to convert them to have a common denominator, which in this case would be 4. After adjusting 1/2 to 2/4, you can then add the two fractions since they now share the same denominator. In contrast, the numerator represents the number of specific parts being considered, and while it can differ when dealing with fractions, the operation itself hinges on the denominators aligning. The whole number part and the decimal value are not relevant in the context of adding or subtracting typical fractions.