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Multiplying By Multiples Of 10 Explained With Simple Steps

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How To Multiply Numbers By Multiples Of 10 With Rules And Examples

The concept of Multiples of 42 is an essential foundation in number theory and arithmetic that students encounter in school maths and competitive exams like JEE and NEET. Knowing how to find and use multiples of 42 is valuable for understanding patterns, division, and solving many higher-level maths problems.


Understanding Multiples of 42

A multiple of 42 is any number that can be expressed as \( 42 \times n \), where \( n \) is an integer (whole number). This means you can create multiples by multiplying 42 by 1, 2, 3, 4, and so on. For example, the first few multiples of 42 are 42, 84, 126, and 168. Recognizing multiples is useful for solving division, factors, and multiples problems in school and Olympiad competitions.


How to Find Multiples of 42

To find multiples of 42, simply multiply 42 by natural numbers:

  • First multiple: \( 42 \times 1 = 42 \)
  • Second multiple: \( 42 \times 2 = 84 \)
  • Third multiple: \( 42 \times 3 = 126 \)
  • And so on: \( 42 \times 4 = 168 \), \( 42 \times 5 = 210 \), ...

You can also get each multiple by repeatedly adding 42 to the previous number. For example: 42 + 42 = 84, 84 + 42 = 126, and so on. This approach emphasizes the connection to repeated addition, a key building block for understanding multiplication.


First 20 Multiples of 42

n Multiple Calculation
14242 × 1
28442 × 2
312642 × 3
416842 × 4
521042 × 5
625242 × 6
729442 × 7
833642 × 8
937842 × 9
1042042 × 10
1146242 × 11
1250442 × 12
1354642 × 13
1458842 × 14
1563042 × 15
1667242 × 16
1771442 × 17
1875642 × 18
1979842 × 19
2084042 × 20

Properties and Related Concepts

  • Every multiple of 42 ends with a digit from the multiples of 2, 3, and 7, because 2 × 3 × 7 = 42 (prime factorization).
  • All multiples of 42 are even numbers, since 42 itself is even.
  • If a number is a multiple of 42, it is also a multiple of 2, 3, and 7.
  • Multiples of 42 are helpful in finding the LCM (lowest common multiple) with other numbers.
  • A multiple common to two numbers (for example, 42 and 30) is called a common multiple.

Worked Examples

Example 1:

Find the 12th multiple of 42.

  1. Write the formula: Multiple = \( 42 \times n \)
  2. Insert n = 12: \( 42 \times 12 = 504 \)

Answer: 504 is the 12th multiple of 42.


Example 2:

Is 336 a multiple of 42?

  1. Divide 336 by 42: \( 336 \div 42 = 8 \)
  2. Since the result is a whole number, 336 is a multiple of 42.

Answer: Yes, 336 is a multiple of 42 (since 42 × 8 = 336).


Example 3:

List all common multiples of 14 and 42 up to 200.

  • Multiples of 14 up to 200: 14, 28, 42, 56, 70, 84, 98, 112, 126, 140, 154, 168, 182, 196
  • Multiples of 42 up to 200: 42, 84, 126, 168
  • Common multiples: 42, 84, 126, 168

Answer: 42, 84, 126, 168


Practice Problems

  • Find the 7th multiple of 42.
  • Which is the least common multiple of 42 and 30?
  • List all multiples of 42 between 400 and 600.
  • Is 225 a multiple of 42? Justify your answer.
  • Write the next three multiples after 672 for 42.

Common Mistakes to Avoid

  • Confusing multiples with factors—remember, multiples are results of multiplication, while factors divide the number exactly.
  • Forgetting to use only natural numbers (1, 2, 3, …) when finding multiples.
  • Assuming multiples are only less than the number—multiples always start from the number itself and go higher.

Real-World Applications

Multiples of 42 appear in daily life when grouping or packaging things. For example, if a shopkeeper puts 42 candies into a box, he can easily count out 84, 126, or 168 candies using the multiples. In music, rhythm patterns may also use 42-beat cycles. Understanding multiples also helps with time calculations, dividing task loads, and organizing events at regular intervals.


Page Summary

This page has explored multiples of 42, explained how to find them, provided worked examples, and highlighted real-world uses. Mastering this basic arithmetic concept is crucial for faster calculations, advanced topics, and competitive exams. At Vedantu, we make learning numbers and patterns fun and easy by using plenty of worked examples and real-world contexts. To deepen your maths skills, check out related topics like Multiples of 4 and Factors of 42, or learn more about Division on Vedantu.


FAQs on Multiplying By Multiples Of 10 Explained With Simple Steps

1. What does multiplying by multiples of 10 mean?

Multiplying by multiples of 10 means multiplying a number by numbers like 10, 20, 30, 40, and so on. These numbers are called multiples of 10 because they are formed by multiplying 10 by a whole number.

  • A multiple of 10 has a 0 in the ones place.
  • Examples: 10, 20, 50, 100, 300.
  • Example calculation: 6 × 20 = 6 × (2 × 10) = (6 × 2) × 10 = 120.
This concept helps simplify multiplication using place value and basic multiplication facts.

2. How do you multiply a number by 10?

To multiply a number by 10, you move the digits one place to the left or add one zero to the end of a whole number. The result is the original number multiplied by 10.

  • Example: 7 × 10 = 70.
  • Example: 45 × 10 = 450.
  • For decimals: 3.4 × 10 = 34 (decimal moves one place right).
This works because multiplying by 10 increases the place value of each digit by one position.

3. How do you multiply by 20, 30, or other multiples of 10?

To multiply by 20, 30, or any multiple of 10, first multiply by the non-zero digit, then multiply by 10. This uses the distributive property of multiplication.

  • Example: 8 × 30 = 8 × (3 × 10).
  • Step 1: 8 × 3 = 24.
  • Step 2: 24 × 10 = 240.
So, 8 × 30 = 240. This method makes multiplying by multiples of 10 quick and accurate.

4. What is the rule for multiplying by multiples of 10?

The rule for multiplying by multiples of 10 is to multiply by the non-zero digit first, then attach the same number of zeros. This applies to whole numbers.

  • Example: 9 × 40 → First 9 × 4 = 36.
  • Then add one zero → 360.
  • Example: 5 × 300 → 5 × 3 = 15, then add two zeros → 1500.
The number of zeros in the multiple of 10 tells you how many zeros to add.

5. Why does multiplying by 10 add a zero?

Multiplying by 10 adds a zero because each digit shifts one place to the left in the place value system. This increases the value ten times.

  • Example: In 6, the 6 is in the ones place.
  • 6 × 10 = 60, where 6 moves to the tens place.
  • Place value increases from 6 ones to 6 tens.
This shift explains why a zero appears in whole-number multiplication by 10.

6. Can you give an example of multiplying a 2-digit number by a multiple of 10?

Yes, multiplying a 2-digit number by a multiple of 10 involves multiplying normally and then adjusting for place value.

  • Example: 24 × 50.
  • Step 1: 24 × 5 = 120.
  • Step 2: Add one zero (because 50 has one zero).
  • Final answer: 1200.
So, 24 × 50 = 1200, using basic multiplication facts and place value.

7. What is the difference between multiplying by 10 and multiplying by 100?

The difference is that multiplying by 10 shifts digits one place left, while multiplying by 100 shifts digits two places left. This changes the number’s value by different place value positions.

  • Example: 8 × 10 = 80.
  • Example: 8 × 100 = 800.
  • For decimals: 4.5 × 100 = 450.
Multiplying by 100 adds two zeros to whole numbers because 100 has two zeros.

8. How do you multiply decimals by multiples of 10?

To multiply decimals by multiples of 10, move the decimal point to the right based on the number of zeros. Each zero shifts the decimal one place.

  • Example: 2.3 × 10 = 23.
  • Example: 2.3 × 100 = 230.
  • Example: 4.6 × 30 → 4.6 × 3 = 13.8, then × 10 = 138.
This method uses place value understanding when multiplying decimals.

9. What are common mistakes when multiplying by multiples of 10?

A common mistake when multiplying by multiples of 10 is forgetting to multiply by the non-zero digit before adding zeros. This leads to incorrect answers.

  • Incorrect: 7 × 40 = 70 (wrong).
  • Correct method: 7 × 4 = 28, then add one zero.
  • Correct answer: 280.
Another mistake is adding too many or too few zeros, so always count the zeros carefully.

10. How does place value help in multiplying by multiples of 10?

Place value helps in multiplying by multiples of 10 because each multiplication by 10 shifts digits to a higher place value. This increases the number’s value systematically.

  • Example: 35 × 20 = 35 × (2 × 10).
  • 35 × 2 = 70.
  • 70 × 10 = 700.
Understanding ones, tens, and hundreds makes multiplying by multiples of 10 faster and easier.