Absolute value
Abs gives the absolute value: the size of a number without its sign. Press 
, type 2, 
, 7, and press 
to leave the bars. Then 
, type 2, and 
. , its absolute value is , so the answer is 10.
Abs gives the absolute value: the size of a number without its sign. Press , type 2, , 7, and press to leave the bars. Then , type 2, and . 2−7=−5, its absolute value is 5, so the answer is 10.
▶ Watch this step in the video (35:39)