An even number can be divided by 2 evenly. An odd number will have a remainder of 1 when divided by 2. 21 is an odd number.
13 is prime so it is not the number. 15 is the product of 3 and 5, two prime numbers, so it fits the conditions. 17 is prime so it is not the number. 19 is prime so it is not the number. 15 is the only odd number between 11 and 21 that fits the conditions. However, if 21 is included in the range, it also is the product of two prime numbers: 3 x 7.
13 15 17 19 21 23 25 27 29 31
19.5 is halfway between 18 and 21
15 in the hexadecimal number system is represented by 21 in the decimal system.
The number at the midpoint of these two numbers is (15 + 27)/2 = 21
15
14 and 21, and 21 and 28 are the number pairs between 15 and 30 that have 7 as their greatest common factor.
21
It is 16. This is because there are five numbers between 11 and 16, and there are five numbers between 16 and 21 :]
, 21, 22, 24, 25, 26, 27, 28
Then number half way between them is their mean average: (-3/7 + -15/14) ÷ 2 = (-6/14 + -15/14) ÷ 2 = -21/14 ÷ 2= -21/28 = -3/4
36 - 21 = 1536 - 21 = 1536 - 21 = 1536 - 21 = 15
No even number gose in 21. In fact there is none that goes in 21, either.
21/0.15 = 140 Therefore, 21 is 15 percent of 140.
21 is an odd composite number
11, 13, 15, 17, 19, 21. 'Inclusive' means you count that number and 'exclusive' means you leave the number out.