Page 91 - ICSE Math 6

6 Decimals

Key Concepts

• Decimals, Decimal Fractions, Decimal Notation • Comparison of Decimals
• Like and Unlike Decimals • Conversion of Fractions into Decimals
• Equivalent Decimals • Conversion of Decimals into Fractions
• Decimals on Number Line • Operations on Decimals and Word Problems

Decimals and Decimal Fractions

The word decimal is related to ten and the fractions having 10 or higher powers of 10 as the denominator
2 11 121
are known as decimal fractions. For example, , and are all decimal fractions. Also, the
10 100 1000
fractions having 10 as the denominator are called tenths, 100 as the denominator are called hundredths
and 1,000 as the denominator are called thousandths. The number of digits in the decimal part of
a number is equal to the number of decimal places in it. For example, the decimal part of 5.956 has
three decimal places.

Extended Place Value Chart

We can extend our Indian place value chart by moving right to the ones place to include decimal
fractions. The place to the right of the ones place is the tenths place. The place to the right of the
tenths place is the hundredths place. The place to the right of the hundredths place is the thousandths
place, and so on.

Thousands Ones

… Thousand Thousand Hundred Hundredth Thousandth …
Ten Ten One Tenth

10,000 1,000 100 10 1 1 1 1
10 100 1000

Decimal Notation
We can use decimal notation to express decimal fractions and mixed
fractions. In the decimal notation: Maths Info
(a) We separate the whole and the fractional part of a decimal number The digits after the decimal
by using a decimal point (·). Also, the whole part is written to the point are read individually.
left of the decimal point and the fractional part is written to the
right of the decimal point.
(b) The first place to the right of the decimal point is known as the first decimal place and it is
occupied by tenths. Similarly, the second decimal place is occupied by hundredths and the third
decimal place is occupied by thousandths, and so on. Let’s learn how to write and read numbers
in decimal notation.

75