What's the missing number and why?

[Alan Medic]

.

[Loz]

20. It's the sum of the squares of each digit in the number before it in the circle. 4x4=16, 1x1 + 6x6 = 37, etc.

Good puzzle. Any more?

[red devil]

Good to see logical Loz is back..;-)

[Alan Medic]

Well done Loz. I'll see what else I've got. Was given a book of all sorts.

[red devil]

Are we there yet?

No, do your puzzle book...

[Alan Medic]

.

[Alan Medic]

I need to learn how to reduce the size.

[red devil]

15

ETA: Hmmmmm, maybe not, if you subtract the left hand number from the right hand number you get the number in the middle e.g. 99-72=27...45-27=18...and based on that 15 works for the missing number, however for the last 3 numbers it doesn't...21-13 =8, not 7 as shown...

[Alan Medic]

Think again Red.....

[Loz]

I was thinking along the same lines as RD and realised the last set stuffed that up.

I think it's 12. I'll let you work out why.

[DulwichFox]

Alan Medic Wrote:

-------------------------------------------------------

> I need to learn how to reduce the size.

Right Click your large image in EDF .. Select Google search.. Right click found image and cut and past image location.

Foxy.

[Tigres Pride]

Add the digits across to get the number below - hence 12

[Alan Medic]

Yes. Well done both.