Carpenters who do rough construction get very proficient at "close-enough" measuring. For example, to quickly draw a line parallel to the edge of a board, you can place a pencil at the end of a combination square and move both the square and pencil along the board. Some combination squares have a hole in the blade for this purpose.
Batteries will keep their charge longer if they’re kept cool. Warmer temperatures will shorten their life. Always recharge a battery right after it is used. Never store an uncharged battery and recharge unused batteries every two months.