Turn on Options|Line Numbers to have EditPad display a number before each line in the left margin.
You can set the default state on the Editor page in the file type configuration. There you can also choose whether word wrap should affect line numbers or not. Tick “count physical lines only” if you do not want word wrap to affect line numbering. Then only the first line of each paragraph gets a line number. Otherwise all lines are numbered.
You may temporarily see negative line numbers if you open a very large file and immediately jump to the end of the file. EditPad scans the file for line breaks from top to bottom and from bottom to top at the same time using two background threads. This allows you to immediately start working with the lines at the top and at the bottom of the file, no matter how large your file is. But EditPad won’t know the correct line numbers for the lines scanned from bottom to top until all line breaks have been counted. So while line break scanning continues in the background, EditPad shows negative line numbers for the bottom half of the file. The last line in the file gets number -1, the penultimate line -2, and so on. When line break scanning is completed the line numbers are updated immediately to positive numbers counting from the start of the file.
Options menu
Options|Column Numbers
File Types|Editor
Go|Go to Position