Date of acquisition: 2015/02/28
Provenance : Allemagne
[+ =] key : direct sum to the screen registry.
[-] key : direct substraction to the screen registry.
[X] and [:] key : the result is added (with [+]) or substracted (with [-]) to the screen registry.
[GT] key : Grand Total - All calculations are added or substracted to the screen registry and to the GT registry.
[C] - [AC] : [C] clears only the screen registry and [AC] clears both.
IR key : number of calculations ([-] or [+] key) since last reset by [AC].
[%] : classical percentage calculation. Example : 10 [x] 4 [%] [Screen : 0.4) [=] (Screen 10.4).
[D%] key : backward variation. Example : 100 [X] 20 [D%] (screen : 125) [-] (screen : 25).
Explanation : 25 = 125 X 20%
Mean calculation : [AC] 2090 [+=] 1111 [+=] 2700 [+=] [: ] [IR] [+=] 1967 !