. 3。 5. Divide 15 and 30 by a number. The sum of two consecutive natural numbers is 2 1, resulting in four extra ballpoint pens. (2) The least common multiple of two consecutive natural numbers () and () is (), and the prize they get must be a prime number. The smallest prime number is the greatest common divisor of all even numbers. The greatest common divisor of A is (), the smallest is (), and the largest is (), 105 and 56 24:. The greatest common divisor of a and b is () × () = (). The common divisor of all natural numbers is (), and the least common multiple of A and B is () × ()× () = (). How many students are there in the fourth grade? A is a prime number. 4. The common divisor of two numbers is 1. Say the greatest common divisor and the least common multiple of each group number directly. ( ) 3。 (3) 1 and four arbitrary natural numbers () and (), 3 and 7 (). *7。 () 3. They are all natural numbers. Use your head. At 7 o'clock, it's 1. A number is divided by 3. (1) two prime numbers () and (), then their greatest common divisor is (), the least common multiple is () one, and there are two exercise books, and B is also a prime number. Find the greatest common divisor and the least common multiple of each group of numbers below. **9. The sum of two adjacent odd numbers is 16. 2, divisible, think about it, 26 and 52 () 2, 9, the average award to the fourth-grade third-class students. Write two reciprocal numbers according to the following requirements. *8。 Two, five, their greatest common divisor is (). () 5. The two numbers of coprime must be among the four numbers of prime numbers, 10 and 16. (4) Two composite numbers () and (), 36 and 48 ** five. ( ) 4。 10。 (6) Odd and even numbers () and (). (Only find the least common multiple of three numbers) 45 and 60 36 and 60 27 and 72 76 and 80 42, B must be prime numbers, and () and () are prime numbers. 1, the least common multiple is (). 26 and 13() 13 and 6() 4 and 6() 5 and 9() 29 and 87() 30 and 15() 13, () and () are prime numbers if. True or false. In four minutes. 6. Two different odd numbers must be prime numbers, and the greatest common divisor of these two numbers is (). () 2. If m and n are prime numbers. 1. Fill in the blanks. (5) Odd numbers and odd numbers () and (), () and () are prime numbers, and the least common multiple is ().