A Z with a horizontal line through it (Ƶ or ƶ) most commonly appears in handwriting as a way to distinguish the letter Z from the number 2. But depending on where you’ve seen it, it can also represent the set of integers in mathematics, a currency symbol, or a letter in certain languages. Here’s what each usage looks like in practice.
Handwriting: Telling Z Apart From 2
The most everyday reason for putting a line through a Z is simple: without it, a handwritten Z and a handwritten 2 can look nearly identical. The short horizontal stroke, or crossbar, cuts across the middle diagonal of the Z and instantly signals “this is a letter, not a number.” Many people pick up this habit in middle school math, right around the time algebra introduces letters into equations full of digits.
The same logic applies to crossing the number 7 with a horizontal bar so it isn’t confused with the number 1. Once you start working with expressions that mix variables and numbers on the same line, small visual distinctions matter. A teacher marking your homework needs to know whether you wrote “2x + z” or “zx + 2,” and a single crossbar solves the problem. Most people who adopt the habit keep it for life because it makes all their writing clearer, not just math.
Mathematics: The Symbol for Integers
In math, a stylized Z with a double vertical stroke (ℤ, called “blackboard bold”) represents the set of all integers: the whole numbers extending infinitely in both directions, including zero (…, −3, −2, −1, 0, 1, 2, 3, …). The letter comes from the German word Zahlen, meaning “numbers,” and its use has been attributed to the mathematician David Hilbert.
When written by hand on a chalkboard or whiteboard, mathematicians often draw a single Z with a horizontal bar through it as a quick stand-in for the full blackboard bold character. If you’ve seen this in a textbook, lecture notes, or online math discussion, it almost certainly refers to the integers. You’ll also see annotated versions like ℤ⁺ for positive integers or ℤ≥ for non-negative integers, but the base symbol is always that barred or double-struck Z.
Currency: The Zairean Zaïre and Fictional Money
The character Ƶ has been used as a currency symbol. Its most notable real-world use was for the zaïre, the former currency of what is now the Democratic Republic of the Congo (used from 1967 to 1997). The barred Z distinguished the currency symbol from an ordinary letter, much like the dollar sign distinguishes $ from S.
You’re more likely to have encountered it in video games. Japanese game franchises, including Dragon Ball and several Capcom titles, use Ƶ as the symbol for “zeni,” the Japanese word for money. It also appears in EVE Online (for the Interstellar Kredit) and Ace Combat 5 (for the Osean Zollar). If you spotted a Z with a line through it on a game screen next to a number, it was functioning as a fictional currency marker.
Languages and Alphabets
Ƶ exists as a distinct letter in a handful of writing systems. It appears in certain African language orthographies and in the Zhuang script used in southern China. It’s also one of the modified Latin letters used to write Saanich (Sencoten), an Indigenous language of the Pacific Northwest. In Unicode, the character has its own code points: U+01B5 for the capital letter and U+01B6 for the lowercase version, confirming it’s treated as a separate letter rather than a decorated Z.
Legacy Computing and Data Entry
The practice of adding strokes to ambiguous characters has deep roots in computing. During the punch card era, programmers wrote code by hand before it was typed onto cards, and a misread character could crash a program. Slashing the zero to separate it from the letter O became standard practice, and the same principle extended to other easily confused pairs like Z and 2. Military radio operators, amateur radio enthusiasts, and weather teleprinter services all adopted similar conventions for the same reason: when letters and numbers share the same line, tiny visual cues prevent costly errors.
Modern fonts and screens have largely eliminated the ambiguity, but the habit persists in handwriting, monospaced programming fonts, and any context where someone needs to be absolutely certain a character won’t be misread.