Aptitude - Odd Man Out and Series - Discussion

To find odd man out series, we are using five procedures.
Those are,

1) Check the sequence is any cubes or squares.

2) To find the relation b/w two following numbers.

3) Any relation b/w the given number like,
Adding or multiply last two get the first digit.
Adding or multiply first two digits get the last digit.
Adding or multiply first and last digit get middle one.

4) That is prime numbers or not.

5) Those numbers are odd or even.

Mostly these types are using formed the odd man out series.

Hai friends any can say an easy steps to find like this oddman out problems.

A number which is divisible by one (i.e 1) and itself (the same number that is given) is called a prime number.

41+2=43.
43+4=47.
47+6=53.
53+8=61.
61+10=71.
71+2=73.
73+4=77.
But there is 83, which was not in same sequence. There must be 77.

Hey how you express above formula in to the sum. tn=t (n-1) +2n.
For example =41 (1-1) +2*1=2.

I agree with praveen.

I am not agree with Vikash and ankita as according to them 73 and 81 both will be the answer.But we have to choose one answer.So correct answer is 81 which is not a prime number

4*10+1, 7*6+1, 6*8-1, 6*9-1, 6*10+1, 7*10+1, 8*9+1,
but there are 9*9= 81

What is prime no?

Hey people it should be 73 also..... because in each case 2 is getting added and in that case 73 doesn't fit!!