Question

If

3   2 = 7
5   4 = 23
7   6 = 47
9   8 = 79

Then

10  9 = ??

Answer 1

(3*2)+(2-1)=7
(5*4)+(4-1)=23
(7*6)+(6-1)=47
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(10*9)+(9-1)=98

Comments

its a multiple of 4 the entry calculation. What i did was as followed. 23-7=16, 47-23=24, 79-47=32, so the difference between each subtraction is 8 so that means 32+8=40 so 79+40=119, am i missing something? Can anyone elaborate?

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That's the same logic I followed. So 119 is not correct??

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if 2*3=3 5*4=6 2*8=7 then 3*5=?
What's this?

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3*2+1=7
5*4+3=23
7*6+5=47
9*8+7=79
therefore
10*9+11=101 ya 10*9+9=99
            indrajeet g(add the odd number)

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becouse this que. is odd even que. there becouse ans is 99

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no sir, odd even nub is not  important .  if this question get like as 2  3 = 7
5  4  = 23 .............. and then 14  13 = ?  to aap kya karoge  to fir kitna time loge solve karne m....

Answer 2

Given series is,
ODD EVEN = RELATION
3 2 7 ( 3*2+1)
5 4 23 (5*4+3)
7 6 47 (7*6+5)
9 8 79 (9*8+7)
Following the series we concluded that, Next term in this series must be,
11 10 119 (11*10+9)

But for confusing, the question term is of different nature of,
10 9 ??

Hence the problem is from a complete series of the following type,

3 2 7 ( 3*2+1)
4 3 14 (4*3+2)
5 4 23 (5*4+3)
6 5 34 (6*5+4)
7 6 47 (7*6+5)
8 7 62 (8*7+6)
9 8 79 (9*8+7)
10 9 98 (10*9+8)
11 10 119 (11*10+9)

Hence the answer must be 98

Comments

98 is correct

Answer 3

(3*2)+1=7
(5*4)+3=23
(7*6)+5=47
(9*8)+7=79
(10*9)+9=99 or (10*9)+8=98........

Comments

3x2+1=7
5x4+3=23
7x6+5=47
9x8+7=79
10x9+9=99

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10x9+"8"=98

Answer 4

I'm curious, why a*b+(b-1)= isn't the correct formula?
it gives correct answer for all given
3 2 = 7
5 4 = 23
7 6 = 47
9 8 = 79
and also does answer for any other numbers, like
5459 5458 = 29800679
and you should not to make calculations like
3+2+2=7
5+4+2+3+2+7=23
7+6+2+5+4+23=47
9+8+2+7+6+47=79
10+9+2+9+8+79=117
where you need to complete all middle steps to get the correct answer in further numbers

or if I'll remove a line from original example:
3 2 = 7
5 4 = 23
deleted line
9 8 = 79
so the "third" line of this example appears to be wrong if we need to sum 9*8 with 5 instead of 7 - 9*8+5=77
so it's can't be the correct answer.
but a*b+(b-1)= works same here.

maybe not all must be too complicated?
IMO

Answer 5

3*2+1=7
5*4+3=23
7*6+5=47
9*8+7=79
10*9+9=99

Answer 6

3*2 = 6 +1  ( adding 1 because 2-1=1)

5*4 = 20+3 (4-1=3)

7*6 = 42+5 (6-1=5)

9*8 = 72+7 (8-1=7)

So by observation, 

10*9 = 90+ 8 = 98 (9-1=8)

So,  answer is 98.

Comments

( adding 1 because 2-1=1) < (1 because 3-2 = 1, 5-4, 7-6 etc)

Answer 7

3*2 +1 =7
5*4 +3 =23
7*6 +5=47

The and will be 98

Answer 8

3+2+2=7
5+4+2+(3+2+7)=23
7+6+2+(5+4+23)=47
9+8+2+(7+6+47)=79
10+9+2+(9+8+79)=117

Comments

Its not the answer answer is 113

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Prime numbers with 5 ,6,7,8 th positions gap inbetween

Answer 9

3 *2+1=7
5 *4+3= 23
7 *6+5 = 47
9*8+7 = 79

Hence,

10*9+8 =98

Comments

According to your solution it should be 10*9+9=99 & solution series should be simply 1 3 5 7 9.
Or we have a similar solution posted by Md Sadique Alam above, but I find it wrong as well, as the series is not starting by 1

Answer 10

ans=98
ie 10*9+8

Comments

a*b+b-1=
10*9+9-1=98