Carahsoft interview question

Write a regular expression to extract the Request ID# from the sample text. Sample Text: Email Type : NEW Request Request Type : Request For Quote Request Version : V Request ID# : 1637451 Agency ID : Subject : Single Mode Cable Request Date : 06-OCT-2015 Reply by Date : 09-OCT-2015 23:59 Mod Level : 0 Mod Date : 06-OCT-2015