numrange is a powerful operator. It can be used for searching numbers within a desired range. You can use it to search for business contacts, addresses, and more. The following example searches for numbers from 1200 to 1230. Use a hypen (-) to separate the lower and upper bound of the two numbers.
Example: numrange:1200-1230
The .. operator
The .. (period period) operator is a shorthand for the numrange operator.
Example: 1200..1230
Both operators return identical results and can be combined with other operators and search terms.
Due to Blogger's Terms of Service and personal ethics, I can only provide the above basic examples. Google does offer some protection against malicious queries with the numrange operator though:
Some protection = Limited protection, it is still possible to work around this "apology". Use this operator wisely and be wary when making payments online!