Reasoning - Number Series

In competitive exams various types of questions on numbers are asked. To solve these types of questions, you require a little common sense. This test depends on these concepts − “ascending order”, “descending order”, “preceded by”, “followed by” etc. Let’s discuss about ascending and descending order with examples.

Ascending Order

Ascending order means arrangement from smallest to greatest.

For example − Suppose we have to arrange following numbers in ascending order: 700, 650, 800, 550. Then the ascending order will be- 550, 650, 700, 800.

Descending Order

Descending order means the arrangement from greatest to smallest.

For example − Suppose we have to arrange this: 377, 490, 289, 356. Then the order will be- 490, 377, 356, 289.

For Example − What should come next in the following number sequence?

2 2 3 2 3 4 2 3 4 5 2 3 4 5 6 2 3 4 5 6

a - 2

b - 7

c - 8

d - 3

e - None of these

Solution − Here the series is as follows

2, 23, 234, 2345, 23456, 234567

So, the answer will be 7.

For Example −

The position of first and fifth digits in the number 84329517 is interchanged. Similarly, the positions of second and sixth digits are interchanged, and so on.

Which of the following will be second element from right end after rearrangement?

Solution −

After making the changes, we get the following arrangement − 95178432. Hence, the second digit from right end is 3.

Quicker Method −

There are 8 digits in the given number. Second digit from right end means 7th digit from left. In this question third and seventh digits are interchanged. Hence, answer will be 3.