# Looking for an equation

#### Earl321

##### New member
Imagine a number line from 1 to 7.
I'm looking for an equation where it returns a value that is on the opposite end of the number line.

if I input 1, it returns 7,
if I input 2, it returns 6,
if I input 7, it returns 1,
etc.

#### pka

##### Elite Member
[imath]P(n)=-n+8[/imath].

#### Jomo

##### Elite Member
Did you notice that the sum of your pairs add up to 8?

I would use the equation x+y = 8 or y = 8-x. This is exactly what pka wrote.

#### jonah2.0

##### Full Member
Beer soaked ramblings follow.
Thank you so much!
You could also play a game of connect the dots.

#### Jomo

##### Elite Member
Beer soaked ramblings follow.

You could also play a game of connect the dots.
You're still playing that game?

#### Subhotosh Khan

##### Super Moderator
Staff member
Imagine a number line from 1 to 7.
I'm looking for an equation where it returns a value that is on the opposite end of the number line.

if I input 1, it returns 7,
if I input 2, it returns 6,
if I input 7, it returns 1,
etc.
Input + Return = 8

Return = 8 - Input