数字 (shù zì) literally combines 数 (shù), meaning 'number' or 'to count', and 字 (zì), meaning 'character' or 'written symbol'. Together, it refers to a written or printed representation of a number — that is, a numeral or digit. It covers single digits (0–9) as well as multi-digit numbers like 25 or 100, especially when focusing on their symbolic form rather than their mathematical value.

This term is widely used in everyday contexts: entering passwords, reading ID numbers, discussing digital technology (e.g., digital payments, QR codes), or learning math. Unlike the word 数 (shù), which refers to the abstract concept of number or quantity, 数字 emphasizes the visual, written, or encoded form — for instance, the '3' on a keypad or the '2024' in a year. It’s neutral in register and appears frequently in both spoken and written Mandarin.