Page 46 - ICSE Math 7

points in one line and the corresponding digits in the same column. Now, do the usual addition and
place the decimal point vertically below the other decimal points in the sum.

Example 5: Find the sum of 45.23, 25, 149.3 and 1.016.

Solution: 45.230 (Converting to like decimals) Try These
25.000 1. What will be the sum of 6.73 and
149.300 14.02?
+ 1.016 2. Which is greater: (14.03 + 1.39) or
220.546 (10.93 + 3.50)?

Subtraction of decimals
To subtract decimals, convert all the decimals into like decimals. Write the smaller number below the
bigger number with the decimal points in a line. Now, do the usual subtraction and place the decimal
point vertically below the other decimal points in the difference.

Example 6: Subtract.

(a) 25.359 from 32.1234 (b) 14.9981 from 20.209

Solution: (a) 32.1234 (Converting to (b) 20.2090 (Converting to
– 25.3590 like decimals) – 14.9981 like decimals)
06.7644 05.2109

Example 7: Simplify 20.678 – 15.9 + 3.1705 – 6.

Solution: After converting to like decimals, After converting to like decimals,
add all the positive numbers add all the negative numbers
together to get: together to get:

20.6780 – 15.9
+ 3.1705 – 06.0

23.8485 – 21.9

Now, perform 23.8485 – 21.9 to get:
23.8485
– 21.9000 (Converting to like decimals)

01.9485

Thus, 20.678 – 15.9 + 3.1705 – 6 = 23.8485 – 21.9 = 1.9485

Multiplication of decimals
To multiply the decimal numbers ignoring their decimal points. Count the total number of decimal
places in the given decimal numbers. Starting from right, put the decimal point in the product
obtained as many places from the right as the total decimal places in the given numbers. If the
number of digits in the product is less than the total number of decimal places, then add zeros to
the left of the product.

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