Help!!!

[amrjm]

Can anyone pls help me with this question?

(3[12]24) (6[24]36)

(5[?]32)

[candy46]

Is this a Walsh one? I have just done one of these where the only answer was to use the middle number and I thought this is the wrong way to do these.

[patricia]

This is a 3 stage operation which does come up occasionally.

There are 2 methods of finding the same answer 20.

(3[12]24) (6[24]36)

(5[ ? ]32)

Method 1

3 x 24 = 72
divide by number on the left plus 3
3 + 3 =6
72 divided by 6 = 12

6 x 36 = 216
divide by number on the left plus 3
6 + 3 = 9
216 divided by 9 = 24

5 x 32 = 160
divide by number on left plus 3
5 + 3 = 8
160 divided by 8 = 20

Method 2

3 x 24 = 72
divide the number on right by 4 = 6
72 divided by 6 = 12

6 x 36 = 216
divide the number on the right by 4 = 9
216 divided by 9 = 24

5 x 32 = 160
divide the number on the right by 4 = 8
160 divided by 8 = 20

Candy46, can you post the question?

Patricia

[amrjm]

Thank you Patricia

[candy46]

I didnt realise you could have 3 step operations!!! Nightmare!

(10{40}100) (5{35}80) (15{?]60)

answer is 15 which works with 1st plus 2nd number x 2

Thanks

[stevew61]

I didnt realise you could have 3 step operations!!! Nightmare!

(10{40}100) (5{35}80) (15{?]60)

answer is 15 which works with 1st plus 2nd number x 2

Thanks

Careful, you must use the outside numbers to make the middle number.

So re-working your logic

100 halved = 50 less 10 =40
80 halved = 40 less 5 = 35

so

60 halved = 30 less 15 = 15

If you fall into the trap of using the middle number you can get in a right muddle, however sometimes as in this case it might give a clue but you must go back to using the two outside numbers to make the middle number.

[candy46]

Excellent Thank you,it was a friend who told me the other way and I thought it was wrong and it was really bugging me, at least now I can see the right way to solve it.

[Pratz]

I got the answer 20, but used a different method -

right number - 12 = middle number.
to cross check i did left number x 4 = middle number.