How to Count in Different Numeral Systems

Roman numerals are still used in the Western world, usually on clocks or for years. ^[2] Even then, Arabic numerals are becoming more popular.

1. 1
   Know the symbols used. Roman numerals have seven basic symbols: I, V, X, L, C, D, and M, each meaning "one", "five", "ten", "fifty", "one hundred", "five hundred", and "one thousand", respectively. Because of how long it can get for some numbers, and because there is no standardized symbol for five thousand or ten thousand (or even a standardized way to write these numbers), you usually will not find Roman numerals being used for actual business.
2. 2
   Start with I, II, and III. These are the numbers one, two, and three, respectively. Each additional symbol from largest to smallest adds to the number.
3. 3
   Write "four" as IV. This means "one less than five". It is uncommon to see it being written as "IIII". A smaller symbol to the left of a larger symbol subtracts from the larger symbol. Thus, IV means "four".
4. 4
   Write "five" as V. To continue adding numbers "six", "seven", and "eight", simply add one, two, and three I's. So six is VI, seven is VII, and eight is VIII.
5. 5
   Write "nine" as IX. Similar to IV (which means "one less than five"), this means "one less than ten".
6. 6
   Write "ten" as X. After ten, numbers are written from largest to smallest order. So XXII is "twenty-two".

   • Note, however, that XXIX means "twenty-nine", not "twenty-six". XIXX is incorrect notation, and so is IXXX.
7. 7
   Write "forty" as XL. Note this when writing numbers involving fours and nines:

   • I (one) goes before V (five) or X (ten) to make four or nine.
   • X goes before L (fifty) or C (hundred) to make forty or ninety.
   • C goes before D (five hundred) or M (one thousand) to make four hundred or nine hundred.
   • Remember that you should only put these before the last symbol of that value, otherwise that notation is incorrect (i.e. don't write XCCC or CMMM, write CCXC or MMCM).
8. 8
   Get the hang of complex numbers. Numbers like MCMXXXIV are pretty long to write and interpret. By breaking the number down into pieces, you can be able to understand the value of it.

   1. Start by counting the number of M's. In this example, M means "one thousand".
   2. Since the second M is preceded by a C, it means "one hundred less than one thousand". This would be "nine hundred". So there are "nine hundreds".
   3. There are three X's, which means "three tens" or "thirty".
   4. Finally, the V is preceded by an I, meaning "one less than five". That would be "four".
   5. Putting it all together, this is one-thousand nine-hundred thirty-four, or 1934.
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This counting system is used primarily where the Chinese language has influenced their vocabulary and systems, including China, Japan, Korea, and Vietnam, although Arabic numerals are becoming dominant even in these areas. ^[3] These may vary based on region and language. Remember to pay attention to stroke order when writing these.

1. 1
   Start with "zero" (written as 零 or 〇). This means that there is absolutely nothing, like "0". Unlike the base ten/decimal system, this is not used as a placeholder in digits.

   • Remember in Chinese that 〇 is rarely used in writing, and is usually only written when it comes to years (2020, 2019, etc.). This means that people sometimes write a year (in this case, 2020) like 二〇二〇 instead of 二零二零, but both ways are still possible.
2. 2
   Write the numbers one to nine as 一, 二, 三, 四, 五, 六, 七, 八, and 九. The pronunciation of these glyphs vary by language, but these characters are essentially each of the numbers one to nine in ascending order.
3. 3
   Write ten as 十. This is also used to mark the "tens" place.
4. 4
   Write eleven as 十一. For the numbers eleven to nineteen, when using Chinese numerals, simply follow the "ten" with any of the glyphs for 1-9.
5. 5
   Write twenty as 二十. For twenty, thirty, forty, fifty, sixty, seventy, eighty, and ninety, write the 十 after the glyphs for 1-9. You can also add how many "ones" you have by following that with another glyph for 1-9.

   • So 三十四 would be interpreted as "thirty-four".
   • Unused positions should be omitted.
6. 6
   Use 百 for "hundreds". For more complicated numbers, it is not recommended that you omit the leading "ones" before each place, as it may make it more difficult to decode these numbers. So 134 should be written as 一百三十四.

   • You can indicate how many "hundreds" you have by filling in the glyphs for 1-9 before the "百".

   Tip: In Chinese, remember to add a 零 if the middle number(s) are blank. Unused zeros at the end are usually omitted, but sometimes when they're in the middle, they're not. So, if it's 1020, you wouldn't write 一千二十, but you would write 一千零二十. This marker is omitted in Japanese.
7. 7
   Use 千 for "thousands". Remember to omit unused positions at the end of a number. So 1100 should be written as 一千一百.
8. 8
   Use 万 for "ten-thousands" and 亿 or 億 for "hundred-millions". Between 10000 and 100000000, use ones, tens, hundreds, and thousands. While there are glyphs for "hundred thousand", "million", and "ten million", they are not commonly used. Same for numbers larger than 999999999.

   • So 12,345,678,902,345 would be written as 十二万三千四百五十六 億 七千八百九十 万 二 千 三 百 四 十 五 (123456 hundred million, 7890 ten-thousands, two thousand three hundred forty five).
   • As you see, the Chinese system does not group digits by threes, as in the Arabic system. When converting from the Arabic system to the Chinese system, it will be prudent to separate the digits into their respective groupings first. For example, you might find it easier to write 12,345,678,902,345 as 123456 7890 2345 first.
9. 9
   Use 点 for decimals. Use this after the ones digit. For example, to write 103.14159, write 一百零三点一四一五七.
10. 10
    Use 负 or 負 for negative numbers. This should be placed before the start of the number. For example, −1,158 should be written as 負一千一百五十八. The meaning of negative numbers varies by context, just like with Arabic numerals.
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1. 1
   Count using binary . To do this, use base two. This is similar to base ten, except it only uses 0's and 1's. So one would be 1, two would be 10, three would be 11, four would be 100, and so on. ^[4]

   Tip : Use 0b before the binary number to avoid confusing the number with decimal, and use spaces or underscores to make the binary digits readable.
2. 2
   Count using octal. To do this, use base eight. This is similar to base ten, except it does not use 8 or 9. So eight would be 10 and fifteen would be 17. ^[5]
3. 3
   Count using hexadecimal. To do this, use base sixteen. This is similar to base ten, except that it also uses six additional symbols: A (ten), B (eleven), C (twelve), D (thirteen), E (fourteen), and F (fifteen). So 10 would be sixteen, and 1E would be thirty-one. ^[6]

   Tip : Use 0x before hexadecimal to avoid confusing it as a standard decimal/base ten number.

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