Arabic Numerals
The numerals used by Western countries have two common forms. "In-line" or "full-height" form is that used on typewriters and taught in North America, in which all numerals have the same height as the majuscule alphabet (i.e., the capital letters). In "old style" text figures, numerals 0, 1, and 2 are x-height; numerals 6 and 8 have bowls within x-height, plus ascenders; numerals 3, 5, 7, and 9 have descenders from x-height, with 3 resembling ʒ; and the numeral 4 extends a bit both up and down from x-height. Old-style numerals are often used by British presses. Aside from these two main forms, other regional variations abound. The numeral one also can be confused with the lower case serif l.
The numeral 0 — Some writers put a diagonal slash through the numeral 0 (zero), a practice that was used on some early, low-resolution computer terminals which displayed a slashed "zero" glyph to distinguish it from the capital letter O. This practice conflicts with the use of the letter "Ø" in the Danish and Norwegian languages. Forms that avoid confusion with Danish include a dot placed in the centre of zero; one with the use of a tick, that is, a slash that does not cross the entire bowl of the figure, but entirely lies in the upper right; a form found in Germany with a completely vertical slash; and one with a slash from upper left to lower right. Confusion between the numeral 0 and the letter O can be resolved by using a script letter O (with a loop at the top), and leaving the numeral 0 without embellishments; this was a common practice before use of the slashed zero became the norm.
The numeral 1 — This numeral is sometimes written with a serif at the top extending downward and to the left. People in some parts of Europe extend this ear nearly the whole distance to the baseline. It is sometimes written with horizontal serifs at the base; without them it can resemble the shape of the numeral 7 which has a near-vertical stroke without a crossbar, and a shorter horizontal top stroke. The numeral often written as a plain vertical line without an ear at the top. This form is easily confused with the capital letter I and with the lower-case letter l.
The numeral 2 — In Germany and Austria a "curly" version used to be taught and is still used by many in handwriting. The 2 can be confused with a capital script Q, or a letter Z.
The numeral 3 — In Taiwan, the top is often written with a diagonal line from the top-left, and the overall figure may be so changed that to foreigners it is completely unrecognizable as even being a number.
The numeral 4 — Some people leave the top "open" — all the lines are vertical or horizontal, as in a seven segment display. This makes it easier to distinguish from the numeral 9. Whether the horizontal bar terminates at or crosses the right vertical bar is insignificant in the West, but to be distinguished from certain Chinese characters it must cross.
The numeral 5 — In Taiwan, the left vertical bar is extended upwards as a long stem. If this is slanted sloppily the overall figure may more closely resemble an uppercase Y. If casually written can be confused with a letter S.
The numeral 6 — Can be confused with a letter capital "G", or the lower case letter "b", or the "9" if inverted. In situations where the number 6 may appear at various angles (such as on billiard balls or some styles of playing cards), it can be underlined (appearing as 6) to indicate the proper viewing angle to disambiguate between 6 and 9; a 9 may or may not appear with similar underlining (as 9).
The numeral 7 — The traditional form found in copperplate penmanship begins with a serif at the upper left and has a wavy horizontal stroke (a swash). In China and Japan, this numeral is commonly written with such a serif, but no swash and no crossbar through the middle. It is usually written with just two strokes, the top horizontal and the (usually angled) vertical. A short horizontal bar sometimes is used to cross the vertical in the middle, to distinguish the seven from a numeral one. This form is used commonly throughout Europe and frequently in Australia. In Taiwan it is possible to use two horizontal bars, although an exaggerated serif is the feature which most clearly distinguishes 7 from 1. When the cross is added in the center it can cause confusion with a script capital F.
The numeral 9 — In parts of Europe, this numeral is written with the vertical ending in a hook at the bottom. This version resembles how the lowercase letter g is commonly written. Elsewhere the usual shape is to draw the vertical straight to the baseline. In South Korea, the 9 is written with the loop above or even to the right of the stick. The backwards version can also be found in Southern Taiwan.
Read more about this topic: Regional Handwriting Variation