Final answer:
To complete the series, add 10 to the last number. The next number after 70 is 80, following the arithmetic sequence pattern where each term is 10 more than the previous term.
Step-by-step explanation:
The series given is an arithmetic sequence where each number increases by 10. To complete this series, you simply add 10 to the last number. Therefore, the sequence proceeds as follows: 30, 40, 50, 60, 70, 80, and so on.
Each term in the series is obtained by adding 10 to the previous term. For example, starting with 30, the next term is 30 + 10 = 40, then 40 + 10 = 50, and continuing in this fashion gives us our pattern. This is one of the simplest types of sequences in mathematics known as an arithmetic sequence, useful in understanding patterns and progressions.