Q1
A number is divisible by 3 if:
Aits digit sum is divisible by 3
Bit is even
Cit ends in 0
Dit is a prime number
CBSEClass 7 (CBSE)MathematicsCh 6 · Topic 2
Divisibility Rules
Learning quick rules to check if a number is divisible by another.
Core concept
Divisibility rules also exist for less commonly used numbers: a number is divisible by 4 if its last two digits form a number divisible by 4; by 6 if it is divisible by both 2 and 3; by 8 if its last three digits form a number divisible by 8; and by 11 using a rule involving alternating digit sums. These rules save significant time when factoring numbers or simplifying fractions, especially with larger numbers where full division would be tedious.
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CBSE class 7 divisibility rules
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• Divisible by 2: last digit is even. Divisible by 5: ends in 0 or 5. Divisible by 10: ends in 0.
• Divisible by 3: digit sum divisible by 3. Divisible by 9: digit sum divisible by 9.
• Divisible by 4: last two digits form a number divisible by 4.
• Divisible by 6: divisible by both 2 and 3.