Number Series Tips and Tricks with Q&A

Number Series Tips and Tricks: Nearly all competitive or banking exams prefer to ask number series based questions in both prelims and mains. The topic is quite straightforward but what makes them tricky to solve is how they are asked. But don’t you worry. We have an answer to each of the tricky question. The key is follow a structured set of directions for approaching the question in a correct manner. So, here are some number series tips and tricks for aspirants:

Number Series Tips & Tricks

A question of number/wrong terms series   

Direction: Find the wrong term in the given series: 800, 678, 579, 497, 434, 385, 349  

1. 494
2. 385
3. 800
4. 579
5. 349

Things to learn:  

• Logics – Notice the pattern of the series. If it’s based on addition, subtraction, cubes, square, etc.
• Sequence to implement these logics – Follow a step-based protocol for recognizing the sequence.

Step-based protocol for sequences (Missing terms)  

• Check if the sequence is based on square, cube, square +, sqaure -, cube +, cube –
• Check if the sequence is based on Multiplication +-, Division +-
• Look for double/triple series is being used
• Look for illogical series is given (rarely given)

Now look for logics as well during these steps. However, for wrong term series you can directly just follow the steps.   

Questions – Prelims Level

1.) What will come in place of the question mark (?) in the following series? 

72, 77, 92, 117, ?, 197 

a.) 136 

b.) 162 

c.) 148 

d.) 152 

e.) None of these 

Answer: d) 

Solution: 

72 + 5 = 77 

77 + 15 = 92 

92 + 25 = 117 

117 + 35 = 152 

152 + 45 = 197 

Hence, option d. 

2.) What will come in place of the question mark (?) in the following series? 

116, 131, ?, 146, 86, 161 

a.) 101 

b.) 98 

c.) 112 

d.) 91 

e.) 111 

Answer: a) 

Solution: 

116+ (15 × 1) = 131 

131 – (15 × 2) = 101 

101 + (15 × 3) = 146 

146 – (15 × 4) = 86 

86 + (15 × 5) = 161 

Hence, option a. 

3.) What will come in place of the question mark (?) in the following series? 

120, 336, 311, 375, 366, ? 

a.) 372 

b.) 368 

c.) 374 

d.) 380 

e.) None of these 

Answer: c) 

Solution: 

120 + 6³ = 336 

336 – 5² = 311 

311 + 4³ = 375 

375 – 3² = 366 

366 + 2³ = 374 

Hence, option c. 

Questions – Mains Level

1.) The following numbers form a series. There is an odd number in the series. If another series is formed using the same pattern and the series starts with the wrong/odd number in the given series, then find the fourth number of the series thus formed. 

36, 44, 68, 120, 196, 316 

a.) 276 

b.) 200 

c.) 228 

d.) 148 

e.) 296 

Answer: b) 

Solution: 

36 + 2 × 4 = 44 

44 + 4 × 6 = 68 

68 + 6 × 8 = 116 

116 + 8 × 10 = 196 

196 + 10 × 12 = 316 

So, fourth number of the series which is 120 is odd number here and following the same pattern starting with 120 is: 

120 + 2 × 4 + 4 × 6 + 6 × 8 = 200  

Hence, option b. 

2.) The following numbers form a series. Find the odd one out. 

225, 481, 815, 1205, 1689, 2265 

a.) 481 

b.) 815 

c.) 1205 

d.) 1689 

e.) None of these 

Answer: b) 

Solution: 

225 + 16² = 481 

481 + 18² = 805 

805 + 20² = 1205 

1205 + 22² = 1689 

1689 + 24² = 2265 

Therefore, 805 should come in place of 815. 

Hence, option b. 

3.) The following numbers form a series. Find the odd one out. 

90, 95, 150, 615, 2480, 12425 

a.) 150 

b.) 615 

c.) 2480 

d.) 12425 

e.) 95 

Answer: a) 

Solution: 

90 × 1 + 5 = 95 

95 × 2 + 10 = 200 

200 × 3 + 15 = 615 

615 × 4 + 20 = 2480 

2480 × 5 + 25 = 12425 

Therefore, 200 should come in place of 150. 

Hence, option a. 

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Number Series Tips – Conclusion

In any of the banking or government exam it is a given that you will have to solve number series questions with the strategy of accuracy and speed. It’s better you divide your time among various category of questions. Solve mini mocks regularly to test your speed and accuracy. 

Start with the basics and then move to the advanced level. Focus on conceptual learning first. Implement speed math methods instead of just learning them. Take regular free mocks at your convenience.    

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