You can perform a Numrange search on any sequential set of numbers by typing two periods between the numbers without any spaces. For example, you could search with the key phrases: fashion icons 1920..1960; cars 30..50 mpg; and computer $500..$800.
Whenever possible, give Google some context for your numbers. Are they miles per gallon, stitches per minute, pounds, or cases? With the exception of dollar signs, you should put a space between your numbers and the keyword that gives those numbers context, just like the car search example.
You'll probably also be more successful if you use an industry standard abbreviation, such as "mpg" rather than spelling out "miles per gallon." When in doubt, you could search for both terms at once by using a Boolean OR search. That would make our car search: cars 30..50 mpg OR "miles per gallon."