Q1
What is a divisibility rule for 3?
ASum of digits divisible by 3
BLast digit is 3
CFirst digit is 3
DNumber of digits is 3
ICSEClass 8 (ICSE)MathematicsCh 5 · Topic 2
Practice and Revision - Playing with Numbers
Let us practise and revise what we learned about playing with numbers. Playing with numbers explores patterns like divisibility rules, numbe
Core concept
Divisibility rules help us quickly check if a number is divisible by another, like a number being divisible by 3 if the sum of its digits is divisible by 3.
How it works
Numbers can be represented generally using letters, like a two-digit number being 10a+b, where a and b represent digits.
Why it matters
This generalisation helps us understand and prove number patterns and tricks, like why reversing digits and subtracting gives a multiple of 9.
Key detail
Exploring these numerical relationships builds deeper mathematical reasoning and prepares us for more advanced algebra.
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Quick notes
• Divisibility rules quickly check number divisibility.
• Divisible by 3 if digit sum is divisible by 3.
• Numbers can be generalised using letters.
• A two-digit number is 10a+b.
• This helps prove number patterns.
• Reversing and subtracting gives a multiple of 9.
• This builds mathematical reasoning.
• It prepares for advanced algebra.