Numio computes your formulas defensively, so a reader never sees a raw spreadsheet error. This article explains what happens when a formula can't produce a number.
How errors are handled at runtime
The engine that computes results for your readers is built to never throw a visible error. Instead of #REF!, #DIV/0!, or #NAME?, it falls back to safe values:
- Unknown functions silently return
0. If a formula calls a function Numio doesn't support, that call evaluates to0rather than failing. (See the functions reference for the supported list.) - Division by zero returns
0instead of infinity or an error. - Empty and non-numeric cells count as
0in arithmetic. - A cell that can't resolve to a number gives
0— for example a result block pointed at a blank or broken cell shows0.
Circular references
If a formula ends up referring back to itself — directly or through a chain of other cells — Numio detects the cycle and returns 0 for the looping reference rather than hanging or crashing. The rest of the workbook still computes normally.
When 0 means "couldn't compute"
Because these fallbacks are silent, a result of 0 can sometimes mean "the formula couldn't compute" rather than "the answer is zero." If a result is unexpectedly 0, check that:
- every function you used is on the supported list,
- referenced cells actually contain values,
- and the formula doesn't reference itself.
The Publish dialog reviews your result formulas before a project goes live and flags any that aren't valid, so broken math is caught there rather than by a reader. See Publishing.
Where to go next
- Formula functions reference — what's supported
- Formula tab overview — the spreadsheet behind your calculator
- Assigning cells to result blocks — wiring results