I. Fill in the blanks (45 points)
1, find all the factors of 24: write one by one from small to large.
2. The multiple of a number is and the minimum multiple is.
3. There are multiples of 2, multiples of 5, multiples of 2 and multiples of 5 in the three digits consisting of numbers 5, 0 and 6.
There are multiples of 2 and 3 in the numbers 36, 75, 34, 366, 580 and 540.
There are multiples of 3 and 5, multiples of 2 and 5, multiples of 2, 3 and 5.
The prime numbers between 5 and 20 are:
6. The smallest odd number is; The smallest prime number is; The smallest composite number is.
7. According to 45 ÷ 5 = 9, we say it is a multiple and a factor.
8. The factor of a number is 24, this number is, and the minimum multiple of this number is.
9. Expressed as the sum of prime numbers: 2 1 =++
10. Fill in a number in □ so that each number is a multiple of 3.
□7 □4 2□ 44□ 6□ 5□ □ 12 1□
1 1, which is not only a multiple of 2 and 5, but also a multiple of 3, with a minimum of three digits.
12, a number with or is a multiple of 5; The numbers in one place are all multiples of 2; The number on a number is a multiple of 3, and this number is a multiple of 3.
13, and the sum of odd and even numbers is; The sum of odd numbers and odd numbers is; The sum of even numbers and even numbers is
There are multiples of 14 and 23, where the minimum multiple is.
15, the unit number is 0, which is both a multiple of and a multiple of.
Two judgments (25 points)
1, the factor of a number must be less than this number. ( )
2. The multiple of a number must be greater than this number. ( )
3. 1 is a factor of any natural number. ( )
4 and 5 are factors and 30 is a multiple. ( )
The unit is 0, which is a multiple of 2 and 5. ( )
The sum of any two odd numbers is even. ( )
7. If a is used to represent a natural number, then 2a must be an even number. ( )
8. The number in a unit is a multiple of 3, and this number is a multiple of 3. ( )
9. If a number is a multiple of 9, it must be a multiple of 3. ( )
10, A is an even number, and the two even numbers adjacent to A are A-2 and A+2 () respectively.
If a is a multiple of 3, then 3a must be a multiple of 9. ( )
12, a natural number, either even or odd. ( )
13, all prime numbers must be odd. ( )
14, the distinction between odd and even numbers is based on whether a number is a multiple of 2. ( )
15, the distinction between prime numbers and composite numbers is based on the number of factors of a number. ( )
16, which is a multiple of 2, is even. ( )
17,7 and 1 1 are all factors. ( )
18, the product of two prime numbers must be a composite number. ( )
19, the sum of two odd numbers must be a composite number. ( )
20. Numbers in units of 3, 6 and 9 are multiples of 3. ( )
2 1, 1, 3, 5, 7 and 9 are all odd numbers. ( )
22. All natural numbers are either odd or even. ( )
23. The sum of two prime numbers is even. ( )
24. 1, 2, 3, 4, 5 ... All are composite numbers except prime numbers. ( )
25. All even numbers are composite numbers and all odd numbers are prime numbers. ( )
Three. Fill in the number of the correct answer in brackets (5 points)
1. If 17 is a multiple of a, then a is ().
A 1 B 17 C 1 or 17
2. Divide 24 by the sum of two prime numbers, and there are () kinds of division. A 2 B 3 C 4
3. 1.8 can be divisible by () A, B, and C.
4. The product of any two natural numbers is (). Prime number b composite number c prime number or composite number
5. If the number A is even, () in the following statement is wrong.
The factor of number A is 2 B, number A is a multiple of 2, and number C is divided by 2, leaving 2.
Five guessing games (5 points)
1 is a multiple of 42 and a multiple of 7. It is also a multiple of 2 and 3. This number is.
2. My factor and minimum multiple are 18. I am.
3. My minimum multiple is 1, and I am.
4. The sum of two prime numbers is 10, and the product is 2 1. They are summer.
5. The sum of two prime numbers is 20 and the product is 9 1. They are summer.
6. Fill in the figures as required (12 points)
1, the sum of five continuous natural numbers is 135, and these five continuous natural numbers are.
2. The sum of five consecutive odd numbers is 135, and these five consecutive odd numbers are.
3. The sum of five consecutive even numbers is 135. These five consecutive even numbers are.
It is both a multiple of 2 and a multiple of 3.
4( ) 7( )0 13( )6 ( ) 12( )
It is both a multiple of 2 and a multiple of 5.
16( ) ( )0 ( )0 ( )75( )
6. It is a multiple of 2, 3 and 5 at the same time.
6( ) ( )70 8( )8( ) 9( )( )0
7 and 8 have four factors: 1, 2, 4, 8 * *, 9 has three factors: 1, 3, 9 * * *, so how many factors does 72 * * have? (3 points)
9. How many different spellings are there to make a rectangle with 48 squares of the same size? (5 points)