Direction In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much-
66.

Look at this series: VI, 10, V, 11, __, 12, III, ... What number should fill the blank?
A. II
 B. IV
C. IX
 D. 14
Answer and Explanation
Answer: B

Explanation: This is an alternating addition and subtraction series. Roman numbers alternate with Arabic numbers. In the Roman numeral pattern, each number decreases by 1. In the Arabic numeral pattern, each number increases by 1.
67.

Look at this series: (1/9), (1/3), 1, ____ , 9, ... What number should fill the blank?
A. (2/3)
 B. 3
C. 6
 D. 27
Answer and Explanation
Answer: B

Explanation: This is a multiplication series; each number is 3 times the previous number.
68.

Look at this series: 83, 73, 93, 63, __, 93, 43, ... What number should fill the blank?
A. 33
 B. 53
C. 73
 D. 93
Answer and Explanation
Answer: B

Explanation: This is a simple subtraction series in which a random number, 93, is interpolated as every third number. In the subtraction series, 10 is subtracted from each number to arrive at the next.




69.

Look at this series: 15, __, 27, 27, 39, 39, ... What number should fill the blank?
A. 51
 B. 39
C. 23
 D. 15
Answer and Explanation
Answer: D

Explanation: In this simple addition with repetition series, each number in the series repeats itself, and then increases by 12 to arrive at the next number.




70.

Look at this series: 72, 76, 73, 77, 74, __, 75, ... What number should fill the blank?
A. 70
 B. 71
C. 75
 D. 78
Answer and Explanation
Answer: D

Explanation: This series alternates the addition of 4 with the subtraction of 3.