Bunuel wrote:
lucalelli88 wrote:
A symmetric number of an another one is a number where the digit are reversed. for istance 123 is the symmetric of one of 321. thus the different of a number and its symmetrical must be divisible by which of the following?
A 4
B 5
C 6
D 7
E 9
I really dont know the answer... can you explain me step by step... thank you for your help;)
A 4
B 5
C 6
D 7
E 9
I really dont know the answer... can you explain me step by step... thank you for your help;)
Let's consider the example of three digit symmetric numbers {abc} and {cba}. Three digit number can be represented as: {abc}=100a+10b+c and {cba}=100c+10b+a. The difference would be:
{abc}-{cba}=100a+10b+c-(100c+10b+a)=99a-99c=99(a-c).
Two digit: {ab} and {ba}. {ab}-{ba}=10a+b-(10b+a)=9a-9b=9(a-b)
Hence the difference of two symmetric numbers (2 digit, 3 digit, ...) will always be divisible by 9.
Answer: E.
i am totally agree with your solution but the question is asking about "the number and difference must be divisible".
can you please expleain