A Date Calculator with BlackBerry Calendar application support. Figure out the date of a deadline so you don't miss it. See how many days you have left until a deadline. Easy to use and accurate. BlackBerry Calendar application support: Launch Calendar application for computed date, Compute date using menu item in Calendar application. Supports the following calculations: Add number of days/weeks to a date, Subtract number of days/weeks from a date, Compute day and week in year for date.