Divisibility by 6
A number is divisible by 6 if it is divisible by both 2 and 3.
Example1: Check if 546 is divisible by 6.
546 is divisible by 2. 546 is also divisible by 3. (Check the divisibility rule of 2and 3 to find out this)Hence 546 is divisible by 6
Example2: Check if 633 is divisible by 6.
633 is not divisible by 2 though 633 is divisible by 3. (Check the divisibility rule of 2 and 3 to find out this).Hence 633 is not divisible by 6
Example3: Check if 635 is divisible by 6.
635 is not divisible by 2. 635 is also not divisible by 3. (Check the divisibility rule of 2 and 3 to find out this)Hence 635 is not divisible by 6
Example4: Check if 428 is divisible by 6.
428 is divisible by 2 but 428 is not divisible by 3.(Check the divisibility rule of 2and 3 to find out this)Hence 428 is not divisible by 6
Divisibility by 7
To find out if a number is divisible by 7, double the last digit and subtact it from the number formed by the remaining digits.Repeat this process until we get at a smaller number whose divisibility we know.
If this smaller number is 0 or divisible by 7, the original number is also divisible by 7.
Example1: Check if 349 is divisible by 7.
Given number = 349
34 – (9 × 2) = 34 – 18 = 16
16 is not divisible by 7. Hence 349 is not divisible by 7
Example2: Check if 364 is divisible by 7.
Given number = 364
36 – (4 × 2) = 36 – 8 = 28
28 is divisible by 7. Hence 364 is also divisible by 7
Example3: Check if 3374 is divisible by 7.
Given number = 3374
337 – (4 × 2) = 337 – 8 = 329
32 – (9 × 2) = 32 – 18 = 14
14 is divisible by 7. Hence 329 is also divisible by 7.
Hence 3374 is also divisible by 7.
Divisibility by 8
A number is divisible by 8 if the number formed by the last three digits is divisible by 8. Example1: Check if 7624 is divisible by 8.
The number formed by the last three digits of 7624 = 624.
624 is divisible by 8. Hence 7624 is also divisible by 8.
Example2: Check if 129437464 is divisible by 8.
The number formed by the last three digits of 129437464 = 464.
464 is divisible by 8. Hence 129437464 is also divisible by 8.
Example3: Check if 737460 is divisible by 8.
The number formed by the last three digits of 737460 = 460.
460 is not divisible by 8. Hence 737460 is also not divisible by 8.
Divisibility by 9
A number is divisible by 9 if the sum of its digits is divisible by 9.
(Please note that we can apply this rule to the answer again and again if we need)
Example1: Check if 367821 is divisible by 9.
3 + 6 + 7 + 8 + 2 + 1 = 27
27 is divisible by 9. Hence 367821 is also divisible by 9.
Example2: Check if 47128 is divisible by 9.
4 + 7 + 1 + 2 + 8 = 22
22 is not divisible by 9. Hence 47128 is not divisible by 9.
Example3: Check if 4975291989 is divisible by 9.
4 + 9+ 7 + 5 + 2 + 9 + 1 + 9 + 8 + 9= 63
Since 63 is big, we can use the same method to see if it is divisible by 9.
6 + 3 = 9
9 is divisible by 9. Hence 63 is also divisible by 9.
Hence 4975291989 is also divisible by 9.
এই লেকচারের পরের পেইজে যেতে নিচের 
…. তে ক্লিক কর।