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Why maths formulas break when a Word file opens on another machine
The paper looks right at home and turns into boxes or shifted symbols at school. What actually causes it, and three fixes by how far you want to go.
The familiar symptom: you write the paper at home and every formula looks right; the same file on the staffroom machine drops fractions onto the baseline, turns Greek letters into boxes, or converts a whole equation into a blurry uneditable picture. This is almost never a corrupt file.
Three causes, and how to tell them apart
A formula in Word exists in three different forms, and each one fails differently. How it breaks tells you which form you have.
- Boxes or question marks instead of symbols — the other machine is missing a font. Equation Editor uses Cambria Math; on a machine without it, every symbol outside the basic alphabet comes out empty.
- The formula is right but sits wrong — different Word versions. Word 2007–2010 and Word 2016 onward lay equations out differently, and any table containing one shifts with it.
- The formula became an uneditable picture — that is a MathType or legacy OLE object. A machine without MathType sees only the last rendered snapshot, and that snapshot breaks up when enlarged.
Fixes, by how far you want to go
- Embed the fonts: File → Options → Save → tick "Embed fonts in the file". This fixes the first cause and takes ten seconds. The file gains a few hundred KB.
- Do not send the .docx — send the PDF. The printout is what students receive, and a PDF does not depend on the printing machine’s fonts or Word build.
- If this happens every week: move the authoring to a tool where the formula does not depend on the reading machine. A page set by the LaTeX engine lands identically everywhere, because it was set before it left your machine.
Texva imports all three forms, legacy MathType objects included, and keeps the formula as editable data. But if this bites you once a year, steps 1 and 2 above are enough — no need to change tools over one file.
Templates for this
- THPT 2025 Exam — Full Three-Part Format (Vietnam)Full THPT 2025 format: multiple-choice + 4-statement true/false + short numeric-answer questions, matching the official 2025 structure.
- 15-Minute Quiz (Vietnam)A single-page quick check: 5 multiple-choice questions plus one short-answer question.
More posts
- The twelve question types a THPT paper can use, and what each one measuresThe twelve types do not measure the same thing. What each one is actually good at, the cognitive level it fits, and the mistake each one invites.
- Marking answer sheets from a photo — what to get right before you printMarking from a photo is far faster than by hand, but a mistake in preparation mismarks a whole room with nothing looking wrong. Four things to settle first.
- Writing a Circular 5512 lesson plan faster without dropping sectionsA Circular 5512 lesson plan is long because it must be complete, not because it needs a lot of writing. The four slowest parts, and which of them can go.