How is the divisibility rule for 7 more complicated then the rules for 2,3,5 and 10?

Divisibility rule of 2: All even numbers are divisible by 2 means no remainder will be left. For example - 4,6,10,18,26 etc

Divisibility rule of 3: A number is divisible by 3 if the sum of the digits is divisible by 3. For example - 15,54,213,699 etc

Divisibility rule of 5: A number is divisible by 5 if the number's last digit is either 0 or 5. For example - 40,85,255,3600,6510 etc

Divisibility rule of 10: The last digit must be zero. For example-100,450,2500,3010,5860 etc

Divisibility rule of 7: To know if a given number is divisible by 7, we will take the last digit of the number and double it. Then we will subtract the result from the rest of the number. If the resulting number is evenly divisible by 7, then the original number is also divisible by 7. For example: 2555, 5509,203, 287 etc

Lets check for 2555. double the last digit. 5 is doubled to 10. Then subtract 10 from 255 this gives 245. 245 is divisible by 7, so 2555 is divisible by 7.

this is the reason, divisibility rule of 7 is complicated as compared to other given number.