Assessment and Learning in Knowledge Spaces (ALEKS) Basic Math Placement Practice Test

What should you do before subtracting two mixed numbers?

1. Convert them to improper fractions

2. Make their denominators the same

3. Change them into decimals

4. Ignore the whole number part

The correct answer is: Make their denominators the same

Before subtracting two mixed numbers, it is essential to make their denominators the same. This step is crucial because mixed numbers consist of both whole numbers and fractions, and in order to accurately perform the subtraction, the fractional parts must be compatible. By ensuring that both fractions have the same denominator, you can effectively combine the fractions after subtracting their numerators. Once the denominators are aligned, the whole numbers can be subtracted separately from one another after the fractions have been accurately subtracted. This method helps maintain clarity and correctness throughout the calculation process, ultimately ensuring that the final answer is accurate. Converting mixed numbers to improper fractions or changing them to decimals can also facilitate easier calculations in some contexts, but making the denominators the same directly addresses the requirement for operating with fractions in subtraction. Ignoring the whole number part would lead to an inaccurate calculation, as the whole numbers represent significant values that contribute to the total outcome.