1. When a positive integer A and B are relatively prime, the largest number that cannot be represented by A and B is A*BAB.
2. A certain bit s[i] = n (integer) + '0' in string
s , convert this bit into a character n s[i] = s[i]-'0' convert this bit into Non-character cout << s cannot output this bit
3. How to judge whether a fraction can be reduced to a finite decimal, first see if the score can be simplified, if it can be simplified, then it can be reduced to the simplest score judgment; if it can't be simplified, just look at the denominator, the prime factor of the denominator is only 2 or only 5 or Only the fractions of 2 and 5 can be converted to finite decimals, otherwise they cannot be converted to finite decimals.