Easy Mistakes to Avoid

A few slips trip people up again and again with mixed numbers.

• Forgetting to add the numerator. When converting, 2 and 3/4 is not just 2 × 4 = 8 fourths; you still add the 3 to get 11/4.
• Leaving an improper answer. After adding, 3/3 should become a whole 1 and get carried, not left sitting as 3/3.
• Subtracting parts that don't fit. If the top fraction is too small, borrow 1 from the whole first instead of getting a negative fraction.

Catching these turns most mixed-number errors into easy fixes.

One last skill: comparing mixed numbers. To see which is bigger, check the whole numbers first — 4 and 1/8 beats 3 and 7/8 outright, because 4 is more than 3 no matter what the fractions do. Only when the whole numbers match do you compare the fractions, lining them up over a common denominator. So 2 and 1/3 versus 2 and 2/5 comes down to 5/15 versus 6/15, which makes 2 and 2/5 the larger. This is why grocery and recipe amounts are quick to rank at a glance.