Which of the following statements is TRUE? Select ALL true statements. (HINT: try different numbers to check each statement.)
1. The absolute value of any number must be a positive number.
2. The opposite of the opposite of a negative number is the same negative number.
3. The number zero is the only number whose opposite is the same as itself.
4. The absolute value of a negative number has the same value as opposite of the same negative number.
5. The absolute value of the opposite of 2 is same as the opposite of the absolute value of 2.
6. If a number is not negative, then the number must be positive