Number series quiz 1

Explanation:

Logic is

2 × 1 + 1 = 3,

3 × 2 + 4 =10,

10 × 3 + 9 = 39,

39 × 4 + 16 = 172….

So in place of 38, it should be 39.

Explanation:

The logic is

8 × 3 – 5 = 19,

19 × 3 – 5 = 52,

52 × 3 – 5 = 151.

151 × 3 - 5 = 448

So in place of 447, it should be 448.

Explanation:

Logic is

4 × 0.5 = 2,

2 × 1.5 = 3,

3 × 2.5 = 7.5,

7.5 × 3.5 = 26.25

In place of 26.75, it should be 26.25.

Explanation:

Logic is

2 × 1 + 1 = 3,

3 × 2 + 4 = 10,

10 × 3 + 9 = 39.

Thus the wrong number is 40, it should be 39.

Explanation:

Starting from the back

106– 70 = 36,

70- 45 = 25,

45 – 29 = 16,

29 – 20 = 9,

20 – 16 = 4,

16 – 15 = 1.

Every difference is perfect square starting from 36 and decreasing. Thus the wrong number is 18, it should be 16.

Explanation:

Logic is that first difference is 3, next difference is 6, 9, so next should be 12 & 15. Therefore, 29 + 12 = 41. Thus, the missing term is 41.

 

Explanation:

Logic is simple division series; each number is one-half of the previous number.

\frac{4}{2} = 2

\frac{2}{2} = 1

\frac{1}{2} = 1/2

\frac{\frac{1}{2}}{2} = 1/4

\frac{\frac{1}{4}}{2} = 1/8

Explanation:

Logic is: This is an alternating division and addition series: First, divide by 2, and then add 8.

664 ÷ 2 + 8 = 340,

332 ÷ 2 + 8 = 174

340 ÷ 2 + 8 = 178

174 ÷ 2 + 8 = 95

Explanation:

Logic is

4 × 1.5 = 6,

6 × 2 = 12,

12 × 2.5 = 30,

30 × 3 = 90,

90 × 3.5 = 315,

315 × 4 = 1260.

Thus the wrong number is 313, it should be 315.

Explanation:

Logic is: This is a simple addition series; each number is 3 more than the previous number.

V + III = VIII

VIII + III = XI

XI + III = XIV

XIV + III = XVII

XVII + III = XX

Thus the wrong term is XVI instead, it should XVII