Decimal numbers

 

What are "decimal numbers"?

Decimal numbers are numbers that have a decimal point, which separates the whole number part and the fractional part. For example, 3.14 is a decimal number, where 3 is the whole number part and 14 is the fractional part. Decimal numbers are useful for representing values that are not whole, such as measurements, fractions, or percentages.

One way to understand decimal numbers is to think of them as fractions with a denominator of 10, 100, 1000, or any power of 10. For example, 0.5 is the same as 5/10, 0.25 is the same as 25/100, and 0.001 is the same as 1/1000. The decimal point indicates how many zeros are in the denominator. For example, 0.01 has two zeros in the denominator, so it is equivalent to 1/100.

Another way to understand decimal numbers is to think of them as place value. Each digit in a decimal number has a value based on its position relative to the decimal point. The digit to the left of the decimal point is the ones place, which has a value of 1. The digit to the right of the decimal point is the tenths place, which has a value of 1/10 or 0.1. As we move further right, each digit has a value that is 10 times smaller than the previous one. For example, the hundredths place has a value of 1/100 or 0.01, and the thousandths place has a value of 1/1000 or 0.001.

To read a decimal number aloud, we say the whole number part followed by “and” and then the fractional part as if it were a whole number with the name of its place value at the end. For example, we read 3.14 as “three and fourteen hundredths”, and we read 0.75 as “zero and seventy-five hundredths” or simply “seventy-five hundredths”.

To write a decimal number in words, we write the whole number part in words followed by a hyphen and then the fractional part in words with the name of its place value at the end. For example, we write 3.14 as “three-point-fourteen” or “three-hyphen-fourteen hundredths”, and we write 0.75 as “zero-point-seventy-five” or “zero-hyphen-seventy-five hundredths”.

Decimal numbers can be used in speech and writing for various purposes, such as:

• Expressing fractions or ratios in a simpler way. For example, instead of saying “one half” or “two fourths”, we can say “zero point five” or “zero point five zero”.
• Expressing measurements or quantities that are not whole or exact. For example, instead of saying “one meter and three centimeters”, we can say “one point zero three meters” or “one point zero three”.
• Expressing percentages or proportions that are not whole or exact. For example, instead of saying “twenty-five percent” or “one fourth”, we can say “zero point two five” or “zero point two five zero”.
• Expressing probabilities or chances that are not whole or exact. For example, instead of saying “one out of four” or “one fourth”, we can say “zero point two five” or “zero point two five zero”.

Decimal numbers are an important part of mathematics and everyday life. They help us represent values that are not whole or exact in a clear and concise way.