Mathematical Notation Rule: Proper Placement of Signs Before Numbers

In mathematics, numbers are categorized as either positive or negative, and this is denoted using a sign. For example, positive numbers might include a "+" sign on the left (though it's often omitted), such as $+3$ or simply $3$, whereas negative numbers require a "-" sign, such as $-3$.

The placement of the sign is crucial for properly understanding the value and meaning of the number. The sign is always placed to the left of the number when it comes to expressing signed numbers on the number line, or anywhere formally outside of a context where postfix notation is specifically used (e.g., for programming or algorithmic purposes).

Therefore, the provided statement "The sign is always written to the left of the number" is indeed True.