Previous Quarter Year Calculation

[BootCam]

I have Quarter Year field in this format, 20183, 20182, 20181, 20174, 20173, 20172, 20171 and so on.

I would like to create a variable for the the previous quarter calculation.

So, When the user select 20183 they will see the current Quarter value and 20182 will be the previous Quarter value.

I was trying with this: =Left(QuarterYear,4)&(Right(QuarterYear,1)-1) but when i select 20181 its giving me 20180 rather than 20174.

Any help?

[BootCam]

[BootCam]

I select 20182 and 20181 its gives me the same value for the calculation where i ignore selections.

[sunny_talwar]

I really can't decipher this by just looking at the image