Reading rules:

1, read in numerical order from the high order.

2. A thousand people study a thousand people, a hundred people study a hundred people, ten people study dozens of people, and a few people study.

3. There is a zero or several zeros in the middle, and the zero is read-only; No matter how many zeros there are at the end, don't read them.

15 is a natural number with two digits. When reading, read according to the reading rules. The number on the tenth place is 1, which is pronounced as ten, and the number on the fifth place is pronounced as five. So 15 is pronounced as: 15.

Extended data:

Properties of 15:

(1) 15 is the16th natural number.

(2) 15 is the 15th positive integer.

(3) 15 is the eighth complex number, and the positive divisor is 1, 3,5, 15. The last one is 14, and the next one is 16.

(4) 15 is the deficit of 13, the sum of true divisors is 9, and the deficit is 6. The last one is 14, and the next one is 16.

(5) 15 is the fourth abnormal composite number and 10 abnormal number, and the prime factor greater than the square root is 5. The last one is 14, and the next one is 17.

(6) 15 is the 6th semi-prime number. The last one is 14, and the next one is 2 1.