There is a following sequence of numbers.
What is the 70th number?
2, 2, 2, 4, 4, 4, 6, 6, 6, 8, 8, 8, ----------
Answer
48
Solution
Since every three of 2, 4, 6, and 8, are located in a line, three numbers are made into one group in this case.
For example, three 6 is the 3rd group.
It is calculated in which group is the 70th number is contained.
Since there are three numbers in 1 group, 70/3=23 remainder 1.
It turns out that the 70th number is the first number of the 23 + 1 = 24th group.
The number of the 2nd group of is 2 × 2 = 4, and the number of the 4th group is 4 × 2 = 8.
Therefore, the number of the 24th group is 24 × 2 = 48.
The 70th number is 48.
