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How Many Times? - Multiplication as Repeated Addition

Grade 3CBSE

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

🔑Concepts

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Multiplication as Repeated Addition: Multiplication is a faster way of adding the same number multiple times. For example, if you see 4 baskets with 3 apples in each, you can visualize this as 3+3+3+33 + 3 + 3 + 3, which is the same as 4×3=124 \times 3 = 12.

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The Multiplication Sign (×\times): The symbol ×\times is used to show multiplication. In the expression 5×25 \times 2, the first number usually tells us the number of groups, and the second number tells us the items in each group. Visually, this looks like 5 pairs of socks laid out in a row.

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Multiplication on a Number Line: You can find the product of two numbers by taking equal-sized jumps on a horizontal number line starting from 00. For 3×43 \times 4, you would visualize 33 big leaps of 44 units each (00 to 44, 44 to 88, and 88 to 1212), finally landing on the answer 1212.

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Rows and Columns (Arrays): Objects arranged in rows and columns form an array. If you have 22 rows of stars with 55 stars in each row, you can see a rectangular grid. The total number of stars is calculated as 2×5=102 \times 5 = 10.

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Skip Counting: Multiplication is closely related to skip counting. To solve 4×54 \times 5, you can skip count by 55s four times: 5,10,15,205, 10, 15, 20. Each count represents adding one more group of 55.

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Order Property (Commutativity): Changing the order of numbers does not change the product. For instance, 33 groups of 44 dots (3×43 \times 4) result in the same total as 44 groups of 33 dots (4×34 \times 3). Both equal 1212.

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Multiplying by Zero and One: When you multiply any number by 11, the answer is the number itself (e.g., 8×1=88 \times 1 = 8). When you multiply any number by 00, the answer is always 00 (e.g., 5×0=05 \times 0 = 0), which is like having 55 empty bags with nothing inside.

📐Formulae

Number of Groups×Items per Group=Total Items\text{Number of Groups} \times \text{Items per Group} = \text{Total Items}

a×b=b×aa \times b = b \times a

n×1=nn \times 1 = n

n×0=0n \times 0 = 0

a+a+...+a⏟b times=b×a\underbrace{a + a + ... + a}_{b \text{ times}} = b \times a

💡Examples

Problem 1:

There are 55 flower pots. Each pot has 44 flowers. How many flowers are there in total?

Solution:

  1. Identify the number of groups: 55 pots.
  2. Identify the number of items per group: 44 flowers.
  3. Write as repeated addition: 4+4+4+4+4=204 + 4 + 4 + 4 + 4 = 20.
  4. Write as multiplication: 5×4=205 \times 4 = 20. Total flowers = 2020.

Explanation:

We use the concept of '5 times 4'. By adding the number 4 five times, we find the total sum.

Problem 2:

Convert the following addition into a multiplication fact: 7+7+77 + 7 + 7.

Solution:

  1. Count how many times the number 77 is being added: It appears 33 times.
  2. The number being added is 77.
  3. Multiplication fact: 3×7=213 \times 7 = 21.

Explanation:

Since 7 is repeated 3 times, we represent this as '3 times 7', which is written as 3×73 \times 7.