Type K - need help on a question please!

[SouthWiltsGrammer]

So, here the numbers in each group are related in some way. I'm wondering if this one is a double operation? I still can't see how it's done though!

(17 [21] 25) (15 [24] 33)

( 12 [___] 46)


Whats the answer and how did you find it?
It was puzzling my daughter this morning and then I couldn't do it

[stevew61]

Add and then halve.

So 12+46= 58 , 58/2=29.

[sonasona]

(17 [21] 25) (15 [24] 33)

( 12 [___] 46)


17 + 25 = 42 halved is 21

15 + 33 = 48 halved is 24

Answer is 12 + 46 = 58 halved is 29

[stevew61]

It was puzzling my daughter this morning and then I couldn't do it

Suggest buy a How To Do VR book, that's what I did.

Type K get easier with practice you get a feel for the numbers.

[SouthWiltsGrammer]

It was puzzling my daughter this morning and then I couldn't do it

Suggest buy a How To Do VR book, that's what I did.

Type K get easier with practice you get a feel for the numbers.

I had that next to me and I still couldn't do it maths wasn't isn't my strongest point, I only got a C grade at GCSE. At least I was right in spotting it was a double operation LOL

[SouthWiltsGrammer]

(17 [21] 25) (15 [24] 33)

( 12 [___] 46)


17 + 25 = 42 halved is 21

15 + 33 = 48 halved is 24

Answer is 12 + 46 = 58 halved is 29

Thank you!!!

[SouthWiltsGrammer]

Add and then halve.

So 12+46= 58 , 58/2=29.

Thank you! I can explain to her tonight now.

[parent2013]

Couldn't resist posting the longer way as you won't be surprised to see if some children might do it this way and end up taking more time for the same question

(17 [21] 25)

17 + 4 = 21, 21 + 4 = 25 where 4 is calc from (25 - 17)/2

(15 [24] 33)

15 + 9 = 24, 24 + 9 = 33 where 9 is calc from (33 - 15) /2


( 12 [___] 46)

(46 - 12)/2 =17

answer is 12 + 17 = 29

[SouthWiltsGrammer]

Couldn't resist posting the longer way as you won't be surprised to see if some children might do it this way and end up taking more time for the same question

(17 [21] 25)

17 + 4 = 21, 21 + 4 = 25 where 4 is calc from (25 - 17)/2

(15 [24] 33)

15 + 9 = 24, 24 + 9 = 33 where 9 is calc from (33 - 15) /2


( 12 [___] 46)

(46 - 12)/2 =17

answer is 12 + 17 = 29

That just boggled my mind!

[mystery]

Oh I see what you mean. Quite often there are two different ways of seeing how the middle number can be calculated from the two outer ones - but I'm not sure that on "first solving" it's necessarily going to be clear to the child which is the quicker route. Time pressure is a tough one if creative thought is truly required too.