New Post: J query for Mobile number validation

HI All,

        I am new to jquery .I need set Phone number Validation for SharePoint 2010 List Item .Can any one help me how can i do it in NewForm.aspx and EditForm.aspx,Which is already having cascading drop-down list code  at"ContentPlaceHolderId="PlaceHolderMain" 

Thanks,

SIDDIQ ALI