This is a very simple icon that is meant to represent the plus sign used in addition. It's made of two lines of exactly the same size crossed over each other so that they run perpendicular. The lines are fairly thick.
This Plus Math icon is made in flat color style
. This format was developed by Icons8 designer team and became immensely popular for use in web and mobile applications. Feel free to download this icon in PNG format for free, or unlock other formats for $5. Unlike other icon packs that have merely hundreds of icons, this monster icon pack contains 6,100 icons, all in the same style and quality.