HP 10bii+ Margin/Markup bug

[ijabbott]

One way it could have been done would be to treat MAR and MU as different views of the same variable. Solving for either MU or MAR would still be based on CST and PRC, but solving for MU would solve for MAR at the same time (and vice versa). Also, inputting MU would automatically calculate MAR (and vice versa). After inputting or solving for one, you could RCL the other without solving.

For example:

25 MU (input markup on cost)
RCL MAR (recall margin on price -> 20)

Or:

100 CST (input cost)
125 PRC (input price)
Then,
MAR (solve for margin on price based on CST and PRC -> 20)
RCL MU (recall markup on cost -> 25)
Alternatively,
MU (solve for markup on cost based on CST and PRC -> 25)
RCL MAR (recall margin on price -> 20)