How do I add or subtract a specific number to a number under the cursor?

Explanation

While <C-a> increments and <C-x> decrements a number by 1, you can prefix either with a count to add or subtract a specific amount. This is incredibly useful when adjusting port numbers, array indices, CSS values, or any numeric constant without mental arithmetic.

How it works

• 100<C-a> — adds 100 to the number under (or after) the cursor
• 5<C-x> — subtracts 5 from the number under the cursor
• Vim finds the first number on or after the cursor position on the current line
• Works with decimal, hex (0x), octal (0), and binary (0b) depending on nrformats

Example

Before (cursor on the line):

server.port = 3000

After pressing 5000<C-a>:

server.port = 8000

Tips

• Combine with . (dot) to repeat: 100<C-a> then press . to add another 100
• Use with <C-x> the same way: 10<C-x> subtracts 10
• In visual mode, {count}<C-a> increments numbers on all selected lines by the same amount
• For sequential numbering across lines, use g<C-a> instead