series

✅ The correct answer is option A.
Alternatively 23 is added and 17 is subtracted from the terms. So, 634 is wrong.

✅ The correct answer is option A.
Each number is twice the preceding one with 1 added or subtracted alternatively.
So, the next number is (2 x 261 + 1) = 523.

✅ The correct answer is option C.
Each of the numbers except 21 is an even number.

✅ The correct answer is option C.
Each of the numbers except 14 is an odd number.

The number ’14’ is the only EVEN number.

✅ The correct answer is option B.
Go on dividing by 6, 5, 4, 3, 2, 1 respectively to obtain the next number. Clearly, 92 is wrong.

✅ The correct answer is option A.
Go on adding 5, 8, 11, 14, 17, 20.
So, the number 47 is wrong and must be replaced by 46.

✅ The correct answer is option A.
Numbers are all primes. The next prime is 43.

✅ The correct answer is option D.
The differences between two successive terms from the beginning are 7, 5, 7, 5, 7, 5.
So, 40 is wrong.

✅ The correct answer is option A.
Each of the numbers except 28, is a multiple of 3.

✅ The correct answer is option B.
Numbers are 13, 23, 33, 43, 53, 63.
So, the missing number is 73 = 343.