1.Divisibility Rules Flashcards
What are the important tricks for checking divisibility by 2?
The last digit of a number should be 0, 2, 4, 6, or 8.
How can you check divisibility by 3?
The sum of the digits should be divisible by 3.
How can you check divisibility by 4?
The last two digits of the number should be divisible by 4.
What are the criteria for checking divisibility by 5?
The last digit of the number should be 0 or 5.
What are the conditions for checking divisibility by 6?
The number should be divisible by both 2 and 3.
How can you check divisibility by 7?
By using the rule of Triplet, if the alternating sum of the digits is divisible by 7.
Example:
Let’s take the number 2,869.
Write the number in reverse order and separate the digits:
Reverse order: 9, 6, 8, 2
Separated digits: 9, 6, 8, 2
Find the alternating sum of the digits:
Alternating sum = 9 - 6 + 8 - 2 = 9
Check if the alternating sum is divisible by 7:
In this case, the alternating sum is 9. Since 9 is not divisible by 7, the original number 2,869 is not divisible by 7.
Therefore, based on the rule of Triplet, the number 2,869 is not divisible by 7.
What is the rule for checking divisibility by 8?
The last three digits of the number should be divisible by 8.
How can you check divisibility by 9?
The sum of the digits should be divisible by 9.
What is the criterion for checking divisibility by 10?
The unit digit of the number should be 0.
How can you check divisibility by 11?
The difference between the sum of odd digits and the sum of even digits should be 0 or divisible by 11.
What are the conditions for checking divisibility by 12?
The number should be divisible by both 3 and 4.
How can you check divisibility by 13?
By using the rule of Triplet, if the alternating sum of the digits is divisible by 13.
