You can increase (abbreviated inc) double-crochet by adding a stitch at the middle or end of the row. When increasing double crochet, always count your stitches to make sure you have the correct number on your work. If you’re working from a pattern, it’ll tell you where to place your extra stitches, so no guesswork is needed.
1- Work across your row until you get to the designated increase stitch or the last stitch of the row.
Crochet the stitches that your pattern calls for. (When increasing stitches, always count your stitches to ensure you have the correct number on your work.)
2- Work 2 stitches into the designated stitch from the previous row.
Here's a look at how to work the stitches and what the finished stitch looks like.
3- Take a look at the symbol for a double crochet increase.
Many people who crochet prefer to read stitch diagrams instead of written instructions. If you see this symbol in the middle or at the end of a row in a pictorial crochet diagram, you'll know it represents a double crochet increase.