GATE Questions

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There should be 90 instead of 80
so we can have a series
5, 5x3, 15x2, 30x3, 90x2, 180x3, 540x2 and 1080x3 and so on...

The cat's foot is called a paw. The horse's foot is called a hoof.

The given number series is 90 72 56 42 36 20

9 x 10 = 90

8 x 9 = 72

7 x 8 = 56

6 x 7 = 42

5 x 6 = 30 (not 36) 

4 x 5 = 20

Hence, the odd man in the given number series is 36.

The given series 24.3, 23.1, 20.7, 17.1, 12.4 follows a pattern that

24.3

24.3 - 1.2 = 23.1

23.1 - 2.4 = 20.7

20.7 - 3.6 = 17.1

17.1 - 4.8 = 12.3 not 12.4

Hence, the odd man or odd number in the given series is 12.4

Here the given number series is 270, 261, 279, 252, 289, 243

270 - 9 = 261

261 + 18 = 279

279 - 27 = 252

252 + 36 = 288 (not equals to 289)

288 - 45 = 243

Hence, the odd number in the given number series is 289.

Given series is 372, 823, 644, 582, 46?, 8?7

Here the series follow the rule that :
372 = 3+7+2 = 12
823 = 8+2+3 = 13
644 = 6+4+4 = 14
582 = 5+8+2 = 15
46? = 4+6+? = 16 => ? = 6
8?7 = 8+?+7 = 17 => ? = 2

So the missing numbers are 6 and 2

504/42 × 7 - 63 + 28 = 84 – 63 + 28 = 49

Hence option 5 is correct.

The given number series is  21 56 102 160 231 316

21      56       102        160      231       316         416

   +35    +46       +58       +71      +85       +100

        +11      +12       +13      +14      +15

Hence, the next number in the given number series is 316 + 100 = 416.