1. The problem is to understand how to represent multiplication in math expressions when the multiplication sign is not explicitly shown. 2. In algebra and arithmetic, multiplication can be implied without a symbol, especially between a number and a variable or between variables. For example, $2x$ means $2 \times x$. 3. The general rule is: when a number is directly next to a variable or parentheses, it implies multiplication. For example, $3(x+2)$ means $3 \times (x+2)$. 4. This helps simplify expressions and makes them easier to write and read. 5. So, if you see something like $ab$, it means $a \times b$, and $4y$ means $4 \times y$. 6. Remember, multiplication is commutative, so $ab = ba$. 7. In summary, the multiplication sign can be omitted when the context is clear, especially between numbers and variables or variables themselves.