1. Decimal Numbers
Decimal numbers are used to display the whole number and fraction together. This whole number and fractional part are separated by inserting a ‘.’, which is known as the decimal point. For example, you are going to buy some grocery items. The store manager says the total bill is £15 and 57 pence. So, to express this amount in one figure, you will express this amount as £15.57. There are many such real-life situations using decimal numbers. We use decimal numbers in our daily lives with money, weight, distance, length, etc.
Decimals lie between integers on the number line. They are one of the ways of representing fractions in Maths.
1.1 Reading Decimal Numbers
The method of reading a decimal number is to first read the whole number followed by ‘point’, then to read the digits in the fractional part separately. For example, we read 96.37 as ninety-six point three seven.
1.2 Adding and Subtracting Decimal Numbers
When adding and subtracting decimals, we line up the decimal points and insert zeros as placeholders if required. Do the calculation in the same way as done for whole numbers addition or subtraction, keeping the decimal point in the answer below the decimal point in the calculation.
For example:
a)4.031 + 5.2 b) 9.563 - 4.42
1.3 Multiplying Decimal Numbers
To multiply a decimal number by 10, 100 and 1000, move the digits to the left as many times as the number of zeros as shown below:
While multiplying two decimal numbers, first, we ignore the decimal point and multiply the two numbers normally. After multiplication, we add the number of decimal places of both the numbers. The answer obtained after multiplication will have the same total number of decimal places. Place the decimal point in the obtained answer.
For example:
a) 75 x 1.5
b) 3.5 x 1.5
1.4 Dividing Decimal Numbers
To divide decimal numbers by 10, 100 and 1000, move the digits to the right as many times as the number of zeros. Remember, when dividing, we may have to cross the decimal point.
We can divide decimals by whole numbers in the same way as we divide two whole numbers. Remember to keep the decimal point of the number above the bus stop in line with the decimal point of the number inside the bus stop. We can divide a decimal by another decimal by converting them using equivalent fractions.
For example, to divide 1.2 by 0.5 we find equivalent fraction of 1.2÷0.5 = 12÷5 and then divide 12 by 5.
For example: Divide 338.56 by 16.
