148
A5 paper is 148 mm wide.
- Even
- Composite
Where 148 fits
Why 148 is special
Halving A4 across its long side gives A5, and the width of A5 is half A4's height. That relationship holds all the way up and down the series because every sheet shares the same square-root-of-two proportion.
Factors & digit properties
- Divisors (6)
- 1, 2, 4, 37, 74, 148
- Prime factorisation
- 2^2 × 37
- Digit sum
- 13
- Digital root
- 4
Representations
- Decimal
- 148
- Scientific notation
- 1.480 × 10^2
Roman numerals
C X L V I I I
CXLVIII uses the subtractive pair XL: ten before fifty — fifty minus ten.
Binary
1 0 0 1 0 1 0 0
1 × 128 + 0 × 64 + 0 × 32 + 1 × 16 + 0 × 8 + 1 × 4 + 0 × 2 + 0 × 1 = 148
Octal
2 2 4
2 × 64 + 2 × 8 + 4 × 1 = 148
Hexadecimal
9 4
9 × 16 + 4 × 1 = 148
Read as powers of two: 128 + 16 + 4 = 148.
In historical numeral systems
Egyptian
1 coil of rope, 4 hobbles, 8 strokes
1 × 100 + 4 × 10 + 8 × 1 = 148. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
2 vertical wedges (sixties place), 2 corner wedges + 8 vertical wedges (units place)
2 × 60 + 28 = 148. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
rho, then mu, then eta, marked as a numeral
rho-mu-eta + keraia
rho + mu + eta written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
qof, then mem, then het
qof-mem-het
qof (100) + mem (40) + het (8) = 148, written in descending order.
Maya
1 bar + 2 dots (upper, twenties place) over 1 bar + 3 dots (lower, units place)
7 × 20 + 8 = 148. Places stack vertically with the smallest at the bottom, so the upper group is worth twenty times the lower.
Systems that simply cannot reach this value are left out. Where a script needs a font most readers do not have, the reading is given instead of the glyphs — see number systems for each system in full.
Other mathematical patterns
- Deficient number
Related numbers & connections
A5 is 148 by 210 mm and A4 is 210 by 297: the width of each size is the height of the next one down. That only works because every sheet shares the square-root-of-two ratio.
View 210 →Mathematically related
- is a factor of210
why?
Strength 0.50, confidence "high".
Everyday life
A5 is 148 by 210 mm — exactly half an A4 sheet, and the same proportions. The width of each size is the height of the next one down, which is only possible because the ratio is the square root of two.
DocumentedEveryday lifeGeography: International outside North America
Common questions
Is 148 a prime number?
No, 148 is not prime.
What are the factors of 148?
The factors of 148 are 1, 2, 4, 37, 74, 148.
What is 148 in Roman numerals?
148 in Roman numerals is CXLVIII. XL is subtractive: ten before fifty — fifty minus ten. Written additively it would be CXXXXVIII, which Roman inscriptions used freely — the strict subtractive form is a later convention.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026