The Scroll Lock key is a remnant from the original IBM PC keyboard. In the original design, Scroll Lock was intended to modify the behaviour of the arrow keys. When the scroll lock mode was on, the arrow keys would scroll the contents of a text window instead of moving the cursor as usual. In this sense, Scroll Lock serves a similar purpose to Num Lock and Caps Lock: it enables a secondary function of a group of keys. Today, this particular use of Scroll Lock is rare.
The number sign can also be inserted into a document by choosing INSERT SYMBOL and selecting the # symbol. In the American English, the # symbol is read as number when it comes before a number. We mostly use the number sign in informal writing, such as emails, texts, journal entries and advertisements. Examples: Do not put a space between the number sign and the number. In the United States, the # symbol is also called the pound sign or pound when it comes after a number. Pound refers to the unit of weight that is abbreviated as lb.
Tri-County Technical College May 2006. Rules for Signed Numbers. Addition. If the signs are the same, add the absolute value and use. the common sign. 3 4 7. p  p p.  6  ( 5)  11.