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\ 01-Oct-2025 Bharat Arora Proof-10 Reader’s Sign _______________________ Date __________

Multiplying by 10, 20, 30, ..., 90, anD 100, 200, 300, ..., 900 3. Find the product.

Multiplying by 10 (a) 50 × 10 (b) 10 × 16 (c) 12 × 30
(d ) 20 × 60 (e) 124 × 10 (f) 8 × 100
To multiply a number by 10, write ‘0’ to the right of the number. 4. Multiply the following.

Look at the following multiplications.
(a) 20 × 700 (b) 500 × 16 (c) 900 × 9
Examples: (a) 3 × 10 = 30 (b) 12 × 10 = 120 (c) 324 × 10 = 3240 (d) 200 × 19 (e) 31 × 300 (f) 17 × 100
Multiplying by 20, 30,..., 90
properties of Multiplication
To multiply a number by 20, 30, 40, ..., 90, first multiply the number without 0. Then,
write ‘0’ to the right of the product. 1. Order Property: Numbers can be multiplied in any

Examples: (a) 12 × 20 = 240 (b) 36 × 30 = 1080 (c) 26 × 60 = 1560 order and their product will remain the same.
Multiplying by 100 12 × 2 36 × 3 26 × 6 Notice that changing the order of two numbers does 4 groups of 3 or 3 groups of 4

To multiply a number by 100, write two zeros (00) to the right of the number. not change the product. = 4 × 3 = 12 = 3 × 4 = 12

Examples: (a) 1 × 100 = 100 (b) 5 × 100 = 500 (c) 12 × 100 = 1200 Examples: (a) 8 × 4 = 32 = 4 × 8 (b) 125 × 10 = 1250 = 10 × 125
Multiplying by 200, 300, ..., 900 2. Multiplication by 1: When a number is multiplied by 1, the product is the number itself.

To multiply a number by 200, 300, 400, ..., 900, first multiply the number without 00. Examples: (a) 7 × 1 = 7 (b) 53 × 1 = 53 (c) 124 × 1 = 124
Then, write two zeros (00) to the right of the product. 3. Multiplication by 0: When a number is multiplied by 0, the product is always '0'.

Examples: (a) 1 × 200 = 200 (b) 12 × 300 = 3600 (c) 14 × 700 = 9800 Examples: (a) 5 × 0 = 0 (b) 17 × 0 = 0 (c) 142 × 0 = 0
1 × 2 12 × 3 14 × 7
estiMating proDuct

Think Tank Critical Thinking
To estimate the product, we first round off the multiplier and the multiplicand to the
Which pair of numbers best completes the given multiplication fact × 100 =
highest place and then, multiply the rounded numbers.
● 65 and 650 ● 10 and 1000 ● 7 and 70 ● 1 and 101
Example: Find the estimated product: 73 × 26 th H t O
Solution: 73 rounded off to the nearest 10 is 70. 7 0
practice time 4e 26 rounded off to the nearest 10 is 30. × 3 0
0 0
1. Fill in the blanks. Now, 70 × 30 = 2100 + 2 1 0 0
Thus, the estimated product = 2100 2 1 0 0
(a) _____ × 10 = 1000 (b) 6 × 100 = _____ (c) 7 × _____ = 3500

(d) _____ × 3 = 2100 (e) _____ × 60 = 480 (f) 11 × 60 = _____

(g) 5 × 20 = _____ (h) 8 × _____ = 320 (i) _____ × 20 = 120 practice time 4F

2. Multiply the following by expanding the bigger number. 1. Fill in the blanks using the properties of multiplication.

(a) 96 × 9 (b) 89 × 5 (c) 36 × 4 (a) 11 × ____ = 11 (b) ____ × 1 = 28 (c) 15 × 6 = ____ × 15
(d) 56 × 9 (e) 64 × 8 (f) 82 × 6 (d) 25 × ____ = 39 × 25 (e) ____ × 29 = 0 (f) 175 × ____ = 0

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