Number Series for SBI PO with Q&A

Number Series for SBI PO: The topic of number series is very popular amongst the SBI PO aspirants. We receive a lot of messages regarding number series doubts and practice questions. So, here we are today to deliver on the same.

Number Series for SBI PO 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 logic as well during these steps. However, for the wrong term series, you can directly just follow the steps.

Number Series for SBI PO – Questions with Answers

Q1.) In the question, three series I, II and III are given. Find the value of x, y and z to establish the correct relation among them and choose the correct option. 

(i) 118, x, 136, 160, 208, 304 

(ii) 945, y, 60, 24, 16, 32 

(iii) 138, 131, 145, z, 152, 117 

a.) x = y > z 

b.) x > y = z 

c.) x = z < y 

d.) y > x < z 

e.) x = y = z 

Answer: c) 

Solution: 

Series I follow the pattern as: 

118 + 6 × 1 = 124 

124 + 6 × 2 = 136 

136 + 6 × 4 = 160 

160 + 6 × 8 = 208 

208 + 6 × 16 = 304 

So, x = 124 

Series II follow the pattern as: 

210 × 4.5 = 945 

60 × 3.5 = 210 

24 × 2.5 = 60 

16 × 1.5 = 24 

32 × 0.5 = 16 

So, y = 210 

Series III follow the pattern as: 

138 – 7 = 131 

131 + 14 = 145 

145 – 21 = 124 

124 + 28 = 152 

152 – 35 = 117 

So, z = 124 

Therefore, x = z < y 

Hence, option c. 

Q2.) A numbers 17, 21, 30, 55, 104, 225 forms a series. 

If 2414 is the n^th term of the above given series, then find the value of n. 

a.) 9 

b.) 13 

c.) 12 

d.) 10 

e.) 11 

Answer: e) 

Solution: 

We are adding square of consecutive prime numbers starting with 2. 

17 + 2² = 21 

21 + 3² = 30 

30 + 5² = 55 

55 + 7² = 104 

104 + 11² = 225 

225 + 13² = 394 

394 + 17² = 683 

683 + 19² = 1044 

1044 + 23² = 1573 

1573 + 29² = 2414 

So, the series is 17, 21, 30, 55, 104, 225, 394, 683, 1044, 1573 and 2414. 

2414 is the eleventh term, so the value of n = 11 

Hence, option e. 

Q3.) The following numbers form a series. One of the numbers in the given series is odd one out. Find the odd number in the series and form a series with same pattern starting with the odd number and then find the sixth number in the new series formed. 

121, 277, 487, 757, 1101, 1521 

a.) [1101, 1197] 

b.) [757, 1617] 

c.) [1101, 2845] 

d.) [1521, 3685] 

e.) [757, 2157] 

Answer: e) 

Solution: 

We are adding multiple of consecutive natural numbers starting with 12 

121 + 12 × 13 = 277 

277 + 14 × 15 = 487 

487 + 16 × 17 = 759 

759 + 18 × 19 = 1101 

1101 + 20 × 21 = 1521 

So, odd number is 757. 

Starting series with 757 we get sixth number as: 

757 + 12 × 13 = 913 

913 + 14 × 15 = 1123 

1123 + 16 × 17 = 1395 

1395 + 18 × 19 = 1737 

1737 + 20 × 21 = 2157 

Hence, option e. 

Q4.) A series is 121, 130, 155, 204, 285, 406. 

If another series __, 83, __, m, __, __ follows the same pattern as the given number series, then find the value of m. 

a.) 161 

b.) 157 

c.) 238 

d.) 108 

e.) 150 

Answer: b) 

Solution: 

121 + 3² = 130 

130 + 5² = 155 

155 + 7² = 204 

204 + 9² = 285 

285 + 11² = 406 

Now, 

74 + 3² = 83 

83 + 5² = 108 

108 + 7² = 157 

157 + 9² = 238 

238 + 11² = 359 

Hence, option b. 

Q5.) The following numbers form a series. Find the odd one out. 

28, 72, 154, 280, 468, 728 

a.) 72 

b.) 154 

c.) 280 

d.) 468 

e.) 728 

Answer: b) 

Solution: 

The series follows the pattern: 

1³ + 3³ = 28, 

2³ + 4³ = 72, 

3³ + 5³ = 152,  

4³ + 6³ = 280, 

5³ + 7³ = 468, 

6³ + 8³ = 728 

Therefore, 152 should be in place of 154. 

Hence, option b. 

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