It's great to categorize number ranges, like people's age for example.

You have a line with each person and their age.

In you list you have age groups, looking like

    Age Age Group
    ...
    19  10-19
    29  20-29
    39  30-39
    49  40-49
    ...

Then you use vlookup to find the group that matches the age, and the non-strict will match 12 to 19, 33 to 39 and so on, returning the age group for that value.