Amount $30.71 written in: 'lowercase', 'UPPERCASE', 'Title Case', 'Sentence case', 'Start Case', 'camelCase', 'hyphen-case' and 'snake_case'.
An amount of money is usually written out in figures using two decimal places (the cents amount, i.e. $12.50, $20.00, $100.45). When exact units of the currency are involved (i.e. $20) it is ok to display no decimal places.
Notes on Letter Cases used to write out in words the number above:
1: Lowercase: only lowercase letters are used. Example: 'seventy-six and two tenths'.
2: Uppercase: only uppercase letters are used. Example: 'SEVENTY-SIX AND TWO TENTHS'.
3. Title Case: first letter of each word is capitalized, except for certain short words, such as articles, conjunctions and short prepositions, 'a', 'an', 'the', 'and', 'but', 'for', 'at', 'by', 'to', 'or', 'in', etc. Example: 'Seventy-Six and Two Tenths'.
4. Sentence case: only the first letter of the first word is capitalized. Example: 'Seventy-six and two tenths'.
5. Start Case: first letter of each word is capitalized without exception. Example: 'Seventy-Six And Two Tenths'.
6. Camel Case: text has no spaces nor punctuation and first letter of each word is capitalized except for the very first letter in the series. Example: 'seventySixAndTwoTenths'.
Pascal Case: See the Camel Case above, but the first letter is also capitalized. Example: 'SeventySixAndTwoTenths'.
7. Hyphen Case: text has no spaces nor punctuation and the words are delimited by hyphen. Example: 'seventy-six-and-two-tenths'. Hyphen Case can be lowercase or uppercase.
8. Snake Case: text has no spaces nor punctuation and the words are delimited by underscore. Example: 'seventy_six_and_two_tenths'. Snake Case can be lowercase or uppercase.
Notes on Writing Out Numbers:
1: It's correct to hyphenate all compound numbers from twenty-one (21) through ninety-nine (99). The hyphen is the minus sign, as in 'thirty-four' (34).
2: In American English, unlike British English, when writing out natural numbers of three or more digits, the word 'and' is not used after 'hundred' or 'thousand': so it is 'one thousand two hundred thirty-four' and not 'one thousand two hundred and thirty-four'.
3. Do not use commas when writing out in words numbers above 999: so it is 'one thousand two hundred thirty-four' and not 'one thousand, two hundred thirty-four'.
4. Use commas when writing in digits numbers above 999: 1,234; 43,290, etc.
Why writing out dollar amounts in words?
Why would anyone write out a dollar amount in words when it is much easier to write it numerically?
You are less likely to make mistakes when you write out the words.
Also, it is a lot harder to alter the amount when you write it out. That is especially important when you write checks or when you have to sign off some official documents that involve significant sums of money.
How to convert amounts of money, USD currency, to words in US American English, as dollars and cents written with letters
How to convert amounts of money, without decimals, to words in US American English?
To write an integer number we first must know the place value of each digit.
For example, the number 1,234,567 has a 1 in the millions place, a 2 in the hundred thousands, a 3 in the ten thousands place, a 4 in the thousands place, a 5 in the hundreds place, a 6 in the tens place, and a 7 in the ones place.
1,234,567 in words is:
= one millions (1,000,000) + two hundred thousands (200,000) + three ten thousands (30,000) + four thousands (4,000) + five hundreds (500) + six tens (60) + seven ones (7)
= one million + two hundred thousands + thirty thousand + four thousand + five hundred + sixty + seven
= one million + (two hundred + thirty + four) thousand + five hundred + sixty + seven
= one million + two hundred thirty-four thousand + five hundred + sixty-seven
= one million two hundred thirty-four thousand five hundred sixty-seven.
So, USD 1,234,567$ = one million two hundred thirty-four thousand five hundred sixty-seven dollars.
1: Note the hyphen (or the minus sign) in "thirty-four" and "sixty-seven" above. Technically, it's correct to hyphenate compound numbers between twenty-one, 21, and ninety-nine, 99.
2: Placement of word "and": in American English do not use the word "and" after "hundred", "thousand" or "million". So, it is "one million two hundred thirty-four thousand five hundred sixty-seven" and not "one million and two hundred thirty-four thousand and five hundred and sixty-seven", though you may hear a lot of people using the last form, informally. On the contrary, the "and" word is always used in British English.