Conditional Formula Question

[Jeremy]

I need to set up a formula that allows the following:

79 or less = 0
80=80
81=81
82=82
100=100
101=102
102=104
103=106
104=108
105=110

Can anyone help?

Thanks

 

[Jeremy]

I have a formula that is set in the cell that will result in 101 however If
that happens i need it to say 102

 

[Fred Smith]

=if(a1<80,0,if(a1>100,(a1-100)*2+100,a1))

Regards,
Fred