Question: User: It's yr 5 what doesn't $$ mean
1. The user is asking about the meaning of $$ in math.
2. In mathematics, $$ is used to indicate that the content inside should be displayed as a block of math, centered and on its own line.
3. This is different from inline math, which is enclosed in single $ symbols and appears within a line of text.
4. For example, inline math: $x+1=2$ appears within a sentence.
5. Display math: $$x+1=2$$ appears centered on its own line for emphasis or clarity.
6. So, $$ means the start and end of a displayed mathematical expression.