I have never used octal numbers in my code nor come across any code that used it. I bet you have. According to the standard, numeric literals which start with zero are octal. This includes, trivially, 0. Every time you have used or seen a literal zero, this has been octal. Strange but true.
If you are making child support payments in Texas, the law generally requires you to do so until your child turns 18, which is the age that marks adulthood in the state, or when he graduates from high school -- whichever comes later.
Thus, when people use the term age of majority, they are generally referring to when a young person reaches the age where one is considered to be an adult. In some states, child support stops when a child is 18 or graduates from high school, in others, it stops at 21.