Practical Vim, 2nd Edition

Tip 10

Use Counts to Do Simple Arithmetic

Most Normal mode commands can be executed with a count. We can exploit this feature to do simple arithmetic.

Many of the commands that are available in Normal mode can be prefixed with a count. Instead of executing the command just once, Vim will attempt to execute the command the specified number of times (see countⓘ).

The <C-a> and <C-x> commands perform addition and subtraction on numbers. When run without a count they increment by one, but if we prefix a number, then we can add or subtract by any whole number. For example, if we positioned our cursor on a 5 character, running 10<C-a> would modify it to read 15.

But what happens if the cursor is not positioned on a numeric digit? The documentation ...