Pronunciation: [fˈɜːst dˈɪd͡ʒɪt] (IPA) 
The spelling of the word "first digit" can be explained using the International Phonetic Alphabet (IPA). The IPA symbol for the "f" sound is /f/, the "er" sound is /ɜːr/, the "s" sound is /s/, and the "t" sound is /t/. The IPA symbol for the "d" sound is /d/ while the "i" sound is /ɪ/ and the "g" sound is /ɡ/. When these IPA symbols are combined, "first digit" is pronounced as /fɜːst ˈdɪdʒɪt/.
First digit refers to the initial numeral or numerical character of a number, specifically in the context of positional numeral systems. In a given number, the first digit is the digit that appears at the leftmost position of the number. This position is often characterized as the most significant digit as it holds the highest value in terms of place value.
In decimal notation, the first digit can be any whole number from 0 to 9, excluding the digit 0 when referring to a positive number. For example, in the number 356, the first digit is 3. Similarly, in the number -9125, the first digit is -9, as negative numbers can also have first digits.
The first digit plays a significant role in determining the overall magnitude or order of a number. It establishes the general range or scale of the number, providing a quick way to assess its magnitude without going into explicit calculation. For instance, if the first digit of a number is 9, it indicates a significantly larger value compared to a number with a first digit of 2 or 3.
In statistical analysis, the first digit phenomenon, also known as Benford's Law, refers to the observation that in many sets of numerical data, the first digit is not equally likely to be any digit from 1 to 9. Instead, the distribution follows a logarithmic pattern, where the digit 1 tends to appear most frequently as the first digit, followed by 2, and so on. This pattern has been observed in various real-life data sets, such as population numbers, financial statements, and mathematical constants.
The word "digit" originates from the Latin word "digitus", meaning "finger" or "toe". It was adopted in mathematics to refer to a numerical symbol representing any of the numbers from 0 to 9. Therefore, the term "digit" is used to describe any one of these ten symbols. The term "first" is an ordinal number derived from Old English, meaning "coming before all others in order or importance". Combining both words, "first digit" means the initial or primary numerical symbol in a sequence or number system.
