Question

What are the next three terms in the sequences below?

1. 2, 5, 7, 12, ___, ___, ___

2. 9, 11, 20, 31, ___, ___, ___

3. 2, 5, 10, 50, ___, ___, ___

4. 1, 3, 3, 9, ___, ___, ___


WRITER

Answer 1

1. 2, 5, 7, 12, 19, 31, 50
- Rule: each term is the sum of the previous two (Fibonacci-type).

2. 9, 11, 20, 31, 51, 82, 133
- Same rule: each term = sum of the previous two.

3. 2, 5, 10, 50, 500, 25,000, 12,500,000
- Rule: each term = product of the previous two (2·5=10, 5·10=50, 10·50=500, …).

4. 1, 3, 3, 9, 27, 243, 6,561
- Same multiplicative rule: each term = product of the previous two.