Neighbor Numbers

Neighbor Numbers is a concept we teach children to help them estimate the value of fractions. Neighbor numbers help us determine the approximate value based upon its relationship to a known fraction.

Neighbor numbers are the fractions for which children have a conceptual understanding, such as ¼, ½, ¾, and 1.

A question involving neighbor numbers might be: ‘Which is larger 7/16 or 4/9?’, the child could compare these to ½. The reason they would pick ½ is because they recognize that:

• 7/16 is 1/16 less than 8/16 = ½
• 4/9 is ½/9 less than 4½/9 = ½ and ½/9 = 1/18
• and since 7/16 and 4/9 are both smaller than ½
• and 1/18 is smaller that 1/16
• then 4/9 is bigger than the 7/16
• because 7/16 is farther away from ½.

Neighbor numbers allow us to use logic instead of common denominators to determine the value of fractions.

Neighbor numbers are often used to quickly put a list of fractions in order from smallest to largest. For example, if you are asked to put these (½ 5/7 1/3 15/31) in order, neighbor numbers are the quickest method, as compared to finding common denominators. This is a very common problem for standardized tests.