Student ID number at a certain University are made up of a letter, followed by six 1-digit numbers, and then another letter (example: L 1323 89M). How many student ID numbers are possible if the letters cannot be repeated?

Satchi found a used bookstore that sells pre-owned dvds and cds. dvds cost $9 each, and cds cost $7 each. satchi can spend no more than $45.

Amountain climber starts a climb at an elevation of 453 feet above sea level at his first rest stop he has climbed 162 feet and by his second rest stop he has climbed another 207 feet its getting late in the day so the climber starts his way down if the climber desends 285 feet how much does he need to ascend or descend to return to the original starting point

The area of a circle is equal to 1 dm². find the radius of the circle.