Sheffer stroke

The Sheffer stroke is a symbol (which looks kind of like a fancy plus sign) used to help solve math problems. It basically means "or," meaning that one thing is true OR another thing is true. For example, if your math problem was "What is 6+7?" you could use the Sheffer stroke to help solve it. That would look like: 6 + 7 = 13 OR 6 + 7 ≠ 13. That says "6 plus 7 is equal to 13 OR 6 plus 7 is not equal to 13." The answer is that 6 plus 7 is equal to 13, so the Sheffer stroke helps you figure that out!