After reconciling requirements, started work on quick solvers.

The plan is to implement at least:

• Quadratic equation solver,
• Cubic equation solver,
• Gain-offset solver,
• Generic root search (for any equation defined in program memory),
• Numeric integration (for any equation defined in program memory),
• Forward probability solver for normal distribution,
• Reverse probability solver for normal distribution.

Below is the approximate sequence for cubic equation Ax^3+Bx^2+Cx+D=0:

1. Enter A into T:, B into Z:, C into Y: and D into X: by any convenient method:

2. Press [F],[A],[√]

3. Read the result

Of course, the same can be achieved by a program, such as
https://github.com/myak555/MK-52_Resurrect/blob/main/MK-52_Sample_Programs/0017_Cubic_Equaton.MK52
but loading a program via File Manager is too time-consuming.