The term "hackstring" was used with multiple different meanings.

Effective character range

The 100 characters (200 on EX model) in the input area that is repeated when [=] is pressed when none of the bytes in the input area is null - in other words, strlen of the input area is at least 100.

Because it's supposed to be impossible to get a formula with more than 99 bytes on the calculator, basic overflow should be used to achieve it.

After basic overflow is achieved, do one of the following to create a formula with more than 99 bytes:

For ES PLUS calculator

  • Enter characters until the cache area is filled.
  • Press [AC] [◀].

Result: The cache area (which is filled) is copied to the input area.

For method that creates a box

Note that the cache area must be clean for this to work. In particular, the byte right after the cursor when step 1 completed must be a null byte.

  • Enter at least 100 (200 for CLASSWIZ) bytes.
  • Press [▶] [▶].
  • (may be necessary) Press [0] [◀] or [0] [DEL].
  • Press [DEL].


This can applies to all methods, but takes more effort and easier to get wrong.

  • Press [0].
  • Enter at least 100 (200 on CLASSWIZ) bytes.
  • Press [◀] exactly the number of characters entered in step 2.
  • Press [DEL] [DEL].

Note that the box is at the begin of the formula.

A formula involving r in an unexpected mode

Note that this meaning is rarely used.


Because the code for calculating r involves calling a function pointer obtained by indexing the sub-mode into an array of pointers, if the sub-mode has an unexpected value, evaluating r will execute some unexpected parts of code.


For calculators with [CALC]

This causes a Syntax ERROR in CLASSWIZ version instead of getting a r.

Do the following steps:

  • In MathIO mode, enter a formula which has the form formula1:formula2 where:
          • formula1 is sufficiently tall, contains at least a variable and should not cause an error when evaluated. (for example e^(e^(e^(e^(e^(e^(e^(e^(e^(e^(e^(e^(e^(X)))))X)))))X))) with X=-1)
          • formula2 evaluates to an answer containing r. For example Pol(1,0), which evaluates to r=1,θ=0.

Then press [CALC], enter values for variables (for example X=-1), repeatedly press [=] until the result of formula2 is displayed, then press [←].

For calculator without [CALC], but with STAT mode

Do the following steps:

  • Enter a mode that is not STAT. (optional, but make the process easier)
  • Enter the STAT submode selection menu.
  • Press [AC], then after approximately 0.5 seconds (about right after the Disp indication disappears) press [ON].
          • This is the probabilistic part. There are no guarantee that it will succeed.
          • If [ON] is pressed too early the calculator will retain in the original mode.
          • If [ON] is pressed too late the calculator will be in submode 1 of STAT mode. Entering STAT menu (for example with [Shift], [1]) will not display the 5:Reg selection, instead 5:Distr is displayed.
  • If it succeed, the calculator will be in submode of STAT mode (normally only submodes 1 to 8 are accessible). Now r is in 5:Reg selection in STAT option menu.


See Applications of r.