Maths Questions- Number Series

Sample Questions of Number Series in Maths

1. The sum of first 25 natural numbers is

(a) 325

(b) 327

(c) 320

(d)  376

Answer: (a)

Explanation:

1+2+3+…..+25

Sum of the First n Natural numbers

The symbol indicates a summation to be carried out.

= 25×13

= 325

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2. Find the sum of 79 consecutive even numbers

(a) 7570

(b) 3560

(c) 6320

(d) 5520

Answer: (c)

Explanation:

2+4+6+. . . +158 (?79th even number is 79×2=158)

= 2(1+2+3+. . . +79)

= 79 × 80 = 632

The sum of first 25 whole numbers is

(a) 300

(b) 325

(c) 375

(d) 385

Answer: (a)

Explanation:

Whole numbers are starting from zero.

So, the sum of numbers from 0 to 24  

4. 

(a) 9070

(b) 7090

(c) 8060

(d) 6080

Answer: (a)

Explanation:

Sum of the squares of the First n Natural numbers,

= 9455-385

= 9070

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5. The sum  is equal to: [SSC Grad. 2000]

(a) 2295

(b) 2425

(c) 2495

(d) 2925

Answer: (a)

Explanation:

Sum of the Cubes of the First n Natural Numbers

=3025-100

=2925