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Multiplication - Properties of Multiplication

Grade 4ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Commutative Property (Order Property): This property states that changing the order of the factors does not change the product. For example, if you have an array of stars with 55 rows and 33 columns (5×3=155 \times 3 = 15), it contains the same number of stars as an array with 33 rows and 55 columns (3×5=153 \times 5 = 15).

Associative Property (Grouping Property): When multiplying three or more numbers, the way in which the numbers are grouped does not change the final result. Imagine three boxes, each containing 22 sets of 44 marbles; whether you calculate (3×2)×4(3 \times 2) \times 4 or 3×(2×4)3 \times (2 \times 4), the total count of 2424 marbles remains the same.

Multiplicative Identity Property (Property of 1): Any number multiplied by 11 gives the number itself as the product. Visually, if you have 77 baskets and each basket has 11 apple, you have a total of 77 apples (7×1=77 \times 1 = 7).

Multiplicative Property of Zero: Any number multiplied by 00 is always 00. If you have 55 empty plates (plates with 00 cookies), the total number of cookies is 00 (5×0=05 \times 0 = 0).

Distributive Property of Multiplication over Addition: This property states that multiplying a sum by a number is the same as multiplying each addend by the number and then adding the products together. For example, to find the area of a large rectangle split into two smaller ones, you can calculate the total width first or find the two smaller areas and add them: 5×(10+2)=(5×10)+(5×2)5 \times (10 + 2) = (5 \times 10) + (5 \times 2).

Terms of Multiplication: In a multiplication sentence like 12×3=3612 \times 3 = 36, the numbers 1212 and 33 are called 'factors', and the result 3636 is called the 'product'. You can visualize this as 'Group Size' ×\times 'Number of Groups' == 'Total'.

Multiplication by 10, 100, and 1000: When a number is multiplied by 1010, 100100, or 10001000, we simply write the number and place one, two, or three zeros respectively to its right. For instance, 45×10045 \times 100 results in 4545 followed by two zeros, which is 45004500.

📐Formulae

a×b=b×aa \times b = b \times a

(a×b)×c=a×(b×c)(a \times b) \times c = a \times (b \times c)

a×1=aa \times 1 = a

a×0=0a \times 0 = 0

a×(b+c)=(a×b)+(a×c)a \times (b + c) = (a \times b) + (a \times c)

Factor×Factor=ProductFactor \times Factor = Product

💡Examples

Problem 1:

Find the product of 25×18×425 \times 18 \times 4 using the Associative Property of multiplication.

Solution:

Step 1: Group the numbers to make multiplication easier. Since 25×4=10025 \times 4 = 100, we group them together: (25×4)×18(25 \times 4) \times 18. \ Step 2: Solve the bracket first: 100×18100 \times 18. \ Step 3: Multiply by 100100 by adding two zeros to the right of 1818: 18001800.

Explanation:

The Associative Property allows us to rearrange the grouping of factors to find 'friendly' numbers like 100100, making the calculation simpler.

Problem 2:

Solve 9×1069 \times 106 using the Distributive Property.

Solution:

Step 1: Break 106106 into a sum of 100+6100 + 6. So, the expression becomes 9×(100+6)9 \times (100 + 6). \ Step 2: Distribute the 99 to both numbers inside the parentheses: (9×100)+(9×6)(9 \times 100) + (9 \times 6). \ Step 3: Calculate the individual products: 900+54900 + 54. \ Step 4: Add the products together: 954954.

Explanation:

The Distributive Property breaks down a complex multiplication problem into two simpler multiplication problems that can be added together.