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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

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.

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.

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.

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.

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.

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.

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+...+ab 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.