Class 6 Mathematics — Chapter 5: Common Multiples and Common Factors

What you'll learn

• ▸Understanding Multiples and Common Multiples
• ▸Identifying Factors and Common Factors
• ▸Prime and Composite Numbers
• ▸The Special Case of Number 1
• ▸The Sieve of Eratosthenes
• ▸Solving Problems with Multiples and Factors
• ▸Perfect Numbers

Chapter Summary

--- PAGE 1 --- 5 PRIME TIME 5.1 Common Multiples and Common Factors 0674CH05 Idli-Vada Game Children sit in a circle and play a game of numbers. One of the children starts by saying '1'. The second player says '2', and so on. But when it is the turn of 3, 6, 9, ... (multiples of 3), the player should say 'idli' instead of the number. When it is the turn of 5, 10, ... (multiples of 5), the player should say 'vada' instead of the number. When a number is both a multiple of 3 and a multiple of 5, the player should say 'idli-vada'! If a player makes any mistake, they are out. The game continues in rounds till only one person remains. For which numbers should the players say 'idli' instead of saying the number? These would be 3, 6, 9, 12, 18, ... and so on. For which numbers should the players say 'vada'? These would be 5, 10, 15, 20, ... and so on. Which is the first number for which the players should say, 'idli-vada'? It is 15, which is a multiple of 3, and also a multiple of 5. Find…

Practice Questions from this Chapter

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1. Explain common multiples simply. Get Solution →
2. Give a real-world example of factors. Get Solution →
3. Quiz me on perfect numbers. Get Solution →
4. In the 'Idli-Vada Game', what is the general term for numbers like 3, 6, 9, ... which are replaced by the word 'idli'? Get Solution →
5. In the 'Jump Jackpot' game, the numbers that represent successful jump sizes to land on 24 (like 1, 2, 3, 4, 6, 8, 12, 24) are called what? Get Solution →
6. According to the text, what is a number that has only two factors (1 and the number itself) called? Get Solution →
7. What is the term for a number that has more than two factors? Get Solution →
8. How does the chapter classify the number 1? Get Solution →

Did you know?

• 💡 The number 496 is also a perfect number, where all its factors add up to twice 496.
• 💡 Some cicada insects emerge from underground every 13 or 17 years, which are prime numbers.
• 💡 A googol is a number so big it's 1 followed by one hundred zeros.
• 💡 All whole numbers have at least two factors: the number one and themselves.
• 💡 Common multiples help engineers design meshing gears for bicycles and machines.

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