Numberwise

668

ISO 668 fixes the dimensions of freight containers.

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Where 668 fits

Where 668 fits: Technology, Related numbersTechnology: Standards issued by an organisation. Related numbers: 6346, 40.TechnologyStandards issued by an orga…Related numbers634640668
668 connects to 2 worlds: technology, related numbers.

Why 668 is special

Standardising the box, rather than the ship or the crane, is what made global container shipping possible, and the twenty-foot unit is still the industry's counting measure.

668 is part of

Standards and specification numbersNumbers around us

Factors & digit properties

Divisors (6)
1, 2, 4, 167, 334, 668
Prime factorisation
2^2 × 167
Digit sum
20
Digital root
2

Representations

Decimal
668
Scientific notation
6.680 × 10^2

Roman numerals

D C L X V I I I

Binary

1 0 1 0 0 1 1 1 0 0

1 × 512 + 0 × 256 + 1 × 128 + 0 × 64 + 0 × 32 + 1 × 16 + 1 × 8 + 1 × 4 + 0 × 2 + 0 × 1 = 668

Octal

1 2 3 4

1 × 512 + 2 × 64 + 3 × 8 + 4 × 1 = 668

Hexadecimal

2 9 c

2 × 256 + 9 × 16 + c × 1 = 668

Read as powers of two: 512 + 128 + 16 + 8 + 4 = 668.

In historical numeral systems

Egyptian

6 coils of rope, 6 hobbles, 8 strokes

6 × 100 + 6 × 10 + 8 × 1 = 668. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.

Babylonian

1 corner wedge + 1 vertical wedge (sixties place), 8 vertical wedges (units place)

11 × 60 + 8 = 668. Places are separated by a space on the tablet, with the higher place written first.

Greek (Ionic)

chi, then xi, then eta, marked as a numeral

chi-xi-eta + keraia

chi + xi + eta written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.

Hebrew numerals

tav, then resh, then samekh, then het

tav-resh-samekh-het

tav (400) + resh (200) + samekh (60) + het (8) = 668, written in descending order.

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

Documented appearance
Standardising the container rather than the ship is what made global container shipping possible.

Standardising the container rather than the ship is what made global container shipping possible.

Connection
One standard fixes the box's dimensions and the other how it is marked, and container shipping needed both.

One standard fixes the box's dimensions and the other how it is marked, and container shipping needed both.

View 6346 →

Numbers Around Us

  • appears inStandards issued by an organisation
    why?

    Strength 0.50, confidence "high".

Other connections

  • is associated with6346
    why?

    Strength 0.50, confidence "high".

  • is associated with40
    why?

    Strength 0.50, confidence "high".

How is 668 connected to another number? →

Technology & computing

  • ISO 668 classifies freight containers by external dimensions and ratings. The twenty-foot equivalent unit derived from it remains the standard measure of container throughput.

    DocumentedTechnology & computingGeography: International — ISO member bodiesPeriod: 1968–

  • CWE-668 is exposure of a resource to the wrong control sphere, the parent class covering permissions, path traversal and information disclosure weaknesses alike.

    DocumentedTechnology & computingGeography: International — MITRE CWEPeriod: 2006–

Common questions

Is 668 a prime number?

No, 668 is not prime.

What are the factors of 668?

The factors of 668 are 1, 2, 4, 167, 334, 668.

What is 668 in Roman numerals?

668 in Roman numerals is DCLXVIII.

About this page's data

Mathematical facts:computed directly from the number's value — nothing to source or verify externally.

Contextual records: 2 reviewer-confirmed records, sourced and reviewed before publication.

Last reviewed: 15 July 2026