Common Core Math Vocabulary

Decimal - Definition with Examples

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What is a decimal number? 
In algebra, a decimal number can be defined as a number whose whole number part and the fractional part is separated by a decimal point. The dot in a decimal number is called a decimal point. The digits following the decimal point show a value smaller than one. 

Here's an example of a decimal number 17.48, in which 17 is the whole number, while 48 is the decimal part. 

Decimals – whole number part and Decimal Part

Decimals are based on the preceding powers of 10. Thus, as we move from left to right, the place value of digits gets divided by 10, meaning the decimal place value determines the tenths, hundredths and thousandths. A tenth means one tenth or 1/10. In decimal form, it is 0.1. Hundredth means 1/100. In decimal form, it is 0.01. 

Decimals Divide by 10 tenths, Hundredths, Thousandths

Here’s an example of how the fractional part can be converted into decimals.

Conversion of mixed number and fractions to decimals

Decimals can be written both in expanded form and in words. 

Decimals – expanded form and written form

Tenths, hundredths, and thousandths can be represented on a number line. To represent tenths, the distance between each whole number on a number line is partitioned into 10 equal parts where each part represents a tenth.

decimals ion number lines

  Fun Facts

  • Decimal fractions were first developed and used by the Chinese in the end of 4th century BC, and then spread to the Middle East and from there to Europe. 

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Instead of teaching decimals and then handing out practice worksheets to your children, give them real life instances in which they can use decimals or convert numbers to decimals. For instance, while shopping, ask your child to compute the price for an item in decimals (half a dozen apples).

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