A decimal point is the dot used to separate the fractional and integer portions of a decimal number. It is one of two commonly used decimal separators, with the other being a comma. Whether a point or comma is used is determined based on the country; in the United States, points are used as the decimal separator.
How to read decimal numbers
The decimal separator is typically read as "point" or "and" depending on the method used to read the decimal number. For example, 6.12 can be read as either "six point one two," or "six and twelve hundredths."
In the first method, the integer portion is read as whatever the integer is, and the decimal separator is read as point. The fractional portion is read as the individual digits.
The second (more formal) method requires an understanding of place value. The integer portion is read in the same way as the first method while the decimal separator is read as "and." The fractional portion is read as an integer along with an indication of the place value of the last digit in the fractional portion.
In 4.56, the last digit is in the hundredths place, so the fractional component is read as "fifty-six hundredths." Similarly, the "7" in 5.7 is read as "seven tenths," the "8" in 3.228 is read as "two hundred twenty-eight thousandths," and so on.
Write the following decimal numbers out in words using both methods described above.
"three point eight nine zero (o) seven"
"three and eight thousand nine hundred seven ten-thousandths"
In the first method, zeros in the fractional portion of a decimal number are often read as "o" for short.
"zero point four nine nine"
"zero and four hundred ninety-nine thousandths"
When the integer portion of a decimal number is 0, sometimes the 0 is omitted. For example, the above example could be written as .499 and read as:
"point four nine nine"
"four hundred ninety-nine thousandths"