Many scraps of paper later a four-digit number emerged, but it was the wrong one.

It draws a four-digit number in the style of Pick 3.

The scarcity of four-digit numbers means that there is a waiting list for them.

It sounded extraordinary, since there are 10,000 possible four-digit numbers.

She picked up a phone and tapped in a four-digit number.

Finally a four-digit number is used to uniquely identify the vehicle.

Take any four-digit number, using at least two different digits.

In this new naming system, components were given four-digit numbers starting with 2.

The number 6174 has the same property for the four-digit numbers.

Leading zeros were added as necessary to give a four-digit number.