The greatest common divisor of 1.8 and 9 is (), and the least common multiple is ().
2. A number has only two divisors, 1 and itself. Such a number is called ().
3. If the number ι is divisible by the number b, then the greatest common divisor of ι and b is () and the least common multiple is ().
4. The prime factor of the decomposition of11is ().
5. Only prime numbers can be filled in brackets:
①26=( )×( )。
② 16=( )+( )=( )+( )。
6. The smallest three digits that can be divisible by 2, 5 and 3 at the same time is ().
7. The product of the minimum prime number multiplied by the minimum composite number should be ().
8. The prime number adjacent to the largest number is ().
Choose the correct result to fill in the blanks.
1. The minimum multiple of the natural number b () its maximum approximate number.
① greater than ② less than ③ equal to
2. Prime number ().
① There is no divisor ② There is only one divisor ③ There are only two divisors ④ There are three divisors.
3. The largest three digits in the following figures that can be divisible by 2, 5 and 3 at the same time is ().
①999 ②996 ③990 ④900
4. The natural number ι is three times the natural number b, the greatest common divisor of these two numbers is (), and the smallest common multiple is ().
①3②③b④ 17 = 1× 17
5. Find the least common multiple of 8, 12 and 60, and the correct one in the following solutions is ().
6. Two numbers are coprime ().
① It must be a prime number ② It must be a composite number ③ The common divisor is only 1.
7.789□ can be divisible by 2, 5 and 3 at the same time.
①0 ② 1 ③2 ④5
Third, the judgment question
1. The tail of a number divisible by 3 and 5 at the same time can only be 5. ( )
The minimum divisor of all natural numbers is 1. ( )
The maximum prime number within 3.50 is 49. ( )
4. The number of A is six times that of B, and B must be the divisor of A .. ()
5. Among the four numbers of 2, 4, 16 and 10, the only number is 2. ( )
6. In a division formula, as long as the quotient is a natural number without remainder, it is called divisibility. ( )
7. The prime factor of a number must be a prime number. ( )
8. All prime numbers are odd, and all composite numbers must be even. ( )
9. Two coprime numbers are not necessarily prime numbers, but two prime numbers must be coprime. ( )
10. The sum of three consecutive natural numbers is 54. These three numbers are 17, 18 and 19 respectively. ( )
Four, the following groups of questions, the left and right questions corresponding to the results, with "-"connection.
1.
① In 35=5×7, 5 and 7 are factors of 35.
② In 6×8=48, 6 or 8 is a prime number.
③ Among the four numbers, 1, 2, 4 and 5, 2 and 5 are prime factors.
2.
A number with only one divisor is a prime number.
(2) Only numbers with two divisors are composite numbers.
③ Numbers with three or more divisors 1
Thinking about the problem:
Can you randomly select five numbers from the table to make their sum equal to 20? Why is mathematics in the fifth grade of primary school?
Examination paper 1
Fill in the blanks
The greatest common divisor of 1.8 and 9 is (), and the least common multiple is ().
2. A number has only two divisors, 1 and itself. Such a number is called ().
3. If the number ι is divisible by the number b, then the greatest common divisor of ι and b is () and the least common multiple is ().
4. The prime factor of the decomposition of11is ().
5. Only prime numbers can be filled in brackets:
①26=( )×( )。
② 16=( )+( )=( )+( )。
6. The smallest three digits that can be divisible by 2, 5 and 3 at the same time is ().
7. The product of the minimum prime number multiplied by the minimum composite number should be ().
8. The prime number adjacent to the largest number is ().
Choose the correct result to fill in the blanks.
1. The minimum multiple of the natural number b () its maximum approximate number.
① greater than ② less than ③ equal to
2. Prime number ().
① There is no divisor ② There is only one divisor ③ There are only two divisors ④ There are three divisors.
3. The largest three digits in the following figures that can be divisible by 2, 5 and 3 at the same time is ().
①999 ②996 ③990 ④900
4. The natural number ι is three times the natural number b, the greatest common divisor of these two numbers is (), and the smallest common multiple is ().
①3②③b④ 17 = 1× 17
5. Find the least common multiple of 8, 12 and 60, and the correct one in the following solutions is ().
6. Two numbers are coprime ().
① It must be a prime number ② It must be a composite number ③ The common divisor is only 1.
7.789□ can be divisible by 2, 5 and 3 at the same time.
①0 ② 1 ③2 ④5
Third, the judgment question
1. The tail of a number divisible by 3 and 5 at the same time can only be 5. ( )
The minimum divisor of all natural numbers is 1. ( )
The maximum prime number within 3.50 is 49. ( )
4. The number of A is six times that of B, and B must be the divisor of A .. ()
5. Among the four numbers of 2, 4, 16 and 10, the only number is 2. ( )
6. In a division formula, as long as the quotient is a natural number without remainder, it is called divisibility. ( )
7. The prime factor of a number must be a prime number. ( )
8. All prime numbers are odd, and all composite numbers must be even. ( )
9. Two coprime numbers are not necessarily prime numbers, but two prime numbers must be coprime. ( )
10. The sum of three consecutive natural numbers is 54. These three numbers are 17, 18 and 19 respectively. ( )
Four, the following groups of questions, the left and right questions corresponding to the results, with "-"connection.
1.
① In 35=5×7, 5 and 7 are factors of 35.
② In 6×8=48, 6 or 8 is a prime number.
③ Among the four numbers, 1, 2, 4 and 5, 2 and 5 are prime factors.
2.
A number with only one divisor is a prime number.
(2) Only numbers with two divisors are composite numbers.
③ Numbers with three or more divisors 1
Thinking about the problem:
Can you randomly select five numbers from the table to make their sum equal to 20? Why?
Reference answer
Examination paper 1
I. 1. (1),(72) 2. (Prime number) 3. (ι)，(b) 4。 ( 1 1 1 = 3× 37)
5.①26=( 13)×(2)② 16=(5)+( 1 1)=(3)+( 13)
6.( 120) 7.(8) 8.(8 or 10)
2. 1. (equal to) 2. (There are only two divisors) 3. (990) 4.(b)、(ι)
5.(②) 6. (The common divisor is only 1) 7.7890
Three. 1.(╳) 2.(√) 3.(╳) 4.(√) 5.(√) 6.(╳) 7.(√) 8.(╳) 9.(√) 65433.
I. 1. (1),(72) 2. (Prime number) 3. (ι)，(b) 4。 ( 1 1 1 = 3× 37)
5.①26=( 13)×(2)② 16=(5)+( 1 1)=(3)+( 13)
6.( 120) 7.(8) 8.(8 or 10)
2. 1. (equal to) 2. (There are only two divisors) 3. (990) 4.(b)、(ι)
5.(②) 6. (The common divisor is only 1) 7.7890
Three. 1.(╳) 2.(√) 3.(╳) 4.(√) 5.(√) 6.(╳) 7.(√) 8.(╳) 9.(√) 65433.