31 in Roman numerals
31 is written XXXI. In chunks: X (10) + X (10) + X (10) + I (1) = 31.
The answer
XXXI
31 in Roman numerals is XXXI.
How XXXI is built
To write it, split 31 into 30 + 1. 30 is XXX, 1 is I, so 31 is XXX then I: XXXI.
To read it, XXXI has 4 chunks, and none of them is a take-away pair, so every chunk is added.
| Chunk | Worth | Why |
|---|---|---|
| X | 10 | Add |
| X | 10 | Add |
| X | 10 | Add |
| I | 1 | Add |
The mistake to watch for
Writing 31 as XXIX
Wrong: XXIX
XXIX has the same letters in a different order, and order matters. A smaller letter before a bigger one means take away, so XXIX is 29, not 31. 31 is XXXI.
Check it with the converter
Type XXIX to see why XXIX is not 31. The rule numbers it gives are the three rules on the Roman numerals page.
Converter set to XXXI (31).
Keep going
Questions parents ask
What is 31 in Roman numerals?
31 is XXXI.
What comes before and after XXXI?
30 is XXX and 32 is XXXII.
Does XXXI use subtraction?
No. Every letter in XXXI is the same size as, or smaller than, the letter before it, so you just add them all.
What is the biggest letter in XXXI?
X, which is 10. XXXI has 4 letters.
Where might you see XXXI?
Rio de Janeiro 2016 was officially the Games of the XXXI Olympiad.
Careful reading is an 11+ skill
Reading all 4 letters of XXXI in order is the careful checking 11+ papers reward. The free diagnostic covers all four subjects, with no card needed.