Question

Ming writes a number pattern on a slip of paper and hands it to his friend Jack. 24 21 23 20 22 19 21 18 Jack writes the next number in the pattern and hands the paper back to Ming. What number should Jack write?

Answer 1

the rule is -3, then +2

24-3 = 21
21 + 2 = 23
23-3= 20
20+2= 22
22-3= 19
19+2 = 21
21-3= 18
18+2 = 20