2, can be 2...: 18, 30, 46, 102 can be 5...: 30, 65.

3. Minimum value: 20, 18 Maximum value: 4,6.

4、6

5.A=24 B= 18 A and B's greatest common factor: 6, 6 A and B's least common multiple: 72,72.

6. Prime numbers: 1 1, 23, 29, 43, 53, 79, and composite numbers: 22, 27, 5 1, 72.

7、

(1), wrong. Natural numbers less than 3 are 0, 1 and 2.

(2) wrong. All positive integers, including 1, prime numbers and composite numbers.

(3) wrong. The coprime of two numbers is a prime number.

(4) wrong. The factors of 12 are 1, 2,3,4,6, 12.

(5) right.

(6) right.

8. The greatest common factor of 11and 7 is1. The least common multiple is 1 1×7=77.

The greatest common factor of 9 and 12 is 3. The least common multiple is 3×3×4=36.

The greatest common factor of 12 and 18 is 6. The least common multiple is 2×3×2×3=36.

The greatest common multiple of 13 and 15 is 13. The minimum common multiple is 13× 1×4=52.

The greatest common multiple of 18 and 24 is 6. The least common multiple is 2×3×3×4=72.

The greatest common factor of 15 and 25 is 5. The minimum common multiple is 5×3×5=75.

9、7×8+ 1

=56+ 1

A: So the next time they meet in the nursing home is May 3rd.

I didn't write the tenth question-