这个number可能只是对relatives 而言

对作为dependent子女的要求不一样：

Qualifying child

In addition to the qualifications above, to claim an exemption for your child, you must be able to answer "yes" to all of the following questions.

• Are they related to you? The child can be your son, daughter, stepchild, eligible foster child, brother, sister, half brother, half sister, stepbrother, stepsister, adopted child or an offspring of any of them.
• Do they meet the age requirement? Your child must be under age 19 or, if a full-time student, under age 24. There is no age limit if your child is permanently and totally disabled.
• Do they live with you? Your child must live with you for more than half the year, but several exceptions apply.
• Do you financially support them? Your child may have a job, but that job cannot provide more than half of her support.
• Are you the only person claiming them? This requirement commonly applies to children of divorced parents. Here you must use the “tie breaker rules,” which are found in IRS Publication 501. These rules establish income, parentage and residency requirements for claiming a child.