40 in Roman numerals
40 is written XL. The smaller X comes before the bigger L, so take it away: XL is 40, ten before fifty.
The answer
XL
40 in Roman numerals is XL.
How XL is built
To write it, 40 is 4 tens and no ones, so it is just the tens: XL. There is no zero to write.
To read it, XL is one take-away pair, so there is nothing else to add.
| Chunk | Worth | Why |
|---|---|---|
| XL | 40 | X before L: take away |
The mistake to watch for
Writing 40 as XXXX
Wrong: XXXX
XXXX writes X four times in a row. Never more than three: 40 is XL, ten before fifty.
Check it with the converter
Type XXXX to see why XXXX is not 40. The rule numbers it gives are the three rules on the Roman numerals page.
Converter set to XL (40).
Keep going
Questions parents ask
What is 40 in Roman numerals?
40 is XL.
What comes before and after XL?
39 is XXXIX and 41 is XLI. XXXIX becomes XL: 39 is 30 + 9, and 40 is 50 take away 10.
Does XL use subtraction?
Yes. X comes before the bigger L, so XL is 40.
What is the biggest letter in XL?
L, which is 50. XL has 2 letters.
Careful reading is an 11+ skill
Reading both letters of XL in order is the careful checking 11+ papers reward. The free diagnostic covers all four subjects, with no card needed.