A plus sign is the symbol + that tells you to add numbers together. When you see 5 + 3, the plus sign in the middle means you should combine those numbers to get 8.

The plus sign is one of the most basic symbols in mathematics, appearing in arithmetic problems from simple addition facts to complex equations. In elementary school, you might see plus signs constantly: What is 12 plus 7? or Add these numbers together. As math gets more advanced, the plus sign stays essential. Even in algebra, when you're working with equations like x + 15 = 42, that familiar symbol still means the same thing it always has.

The plus sign also shows up outside of math problems. On a thermometer, plus 10 degrees means 10 degrees above zero. When someone talks about the plus side of a situation, they mean the positive or good aspects. A plus sign next to a grade like B+ means slightly better than the regular grade.

The symbol itself looks like a cross with equal arms, and mathematicians chose it because it's simple, clear, and easy to write quickly while solving problems.