Example No. 1: 17, 23, 29, 35, ?, 47
Solution:In this case, 6 has been added to all the numbers to generate the next number. Firstly 17 + 6 = 23, then 23 + 6 = 29 and so on. In order to get the next number after 35, 6 would bea dded in that. Therefore, the question mark should be replaced by 35 + 6 = 41.
Example No. 2: 1, 2, 5, 10, 17, 26, ?
Solution: In this example, the odd numbers have been added in the increasing order. Firstly 1, then 3, then 5and 9 in the end. Then, in order to obtain the next number, 11 should be added.Therefore, the next number would be 26 + 11 = 37.
Example No. 3: 4, 4, 8, 24, 96, 480, ?
Solution: In this question,every number is multiplied by the next natural number starting with 1. You can understand this from the following diagram.
The next number, as is clear from the above illustration, would be obtained by multiplying the last number 480 by 6. So the answer is 480 * 6 = 2880
Example No. 4: 2, 10, 30, 68, ?, 222
Solution:In this question, the method of adding the same/different number in the perfect cubes of the natural numbers, is applied. Here in this case, the cube of a natural number is added to the number. I.e. these numbers are 13 + 1, 23 + 2, 33+ 3, 43 + 4, and the answer would be 53 + 5 Þ 130.
Example No. 5: 0, 2, 6, 12, ?, 30
Solution:In this question, from the square of a natural number, the same number has been subtracted. The numbers are obtained as 12 - 1, 22 - 2, 32 -3, 42 – 4. Therefore the next number would be 52 – 5 =20.
* Double Series:Much more common in tests are questions on double number series. In such questions, two series are mixed up alternately. Have a look at the following example.
Example No. 6: 5, 5, 15, 7, 45, 11, 135, 13, 405, ?
Solution: In this question two series run concurrently. Whenever two series are going on, naturally, every alternate term would be belonging to the other series. You may analyze this from the following diagram.
It can be seen clearly that one series out of these is of prime numbers while the other series is number multiplied by 3. Apparently, the missing number belongs to the category of prime numbers, so the next prime number after 13 is 17 and is the right answer.
Example No. 7: 6 6.5 7.5 9 11 13.5 ?
Solution:In this question, the addition factor is increasing continuously by 0.5. The first addition done is 0.5,the second is 1, the third is 1.5 and so on. In the last the addition to be done is 2.5 + 0.5 = 3. So the answer would become 13.5 + 3 = 16.5.
Example No. 8: 4 9 17 35 69 139 ?
Solution:In this question, the logic applied is ´ 2 + 1 and ´ 2 – 1 alternately. In the end what is done is ´ 2 + 1 and in order to get the next term ´ 2 – 1 is to be done. So the answer would be 139 ´ 2 – 1 = 277.
Example No. 9: 2 2 3 6 15 45 ?
Solution:In this question, the multiplier increases by 0.5 each time. Firstly multiplied by 1, then by 1.5,then by 2, then by 2.5 and so on. In the question the second last given number has been multiplied by 3 to get the last number. Now in order to obtain the next number, we should multiply the last number by 3.5. Then answer would be 45´ 3.5 = 157.5.
Example No. 10: 23, 35, 57, 711, 1113, ?
Solution:In this question, the logic is very simple. Two consecutive prime numbers have been combined and represented as a single number i.e. 2 and 3 Þ, then 3 and 5 Þ 35, then 5 and 7 Þ 57 and so on. Every number starts with the same prime number with which the last prime number ended. The next prime numbers to betaken are 13 and 17 and the number would be 1317.
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