Fractions and Decimals

Level 4

Fractions are formed by combining an ordinal number with -osa (part). Decimals always use a comma (pilkku) instead of a point.

How It Works

In Finnish, fractions and decimals require attention to case agreement and specific vocabulary.

1. Fractions (-nnes and -osa)
The standard way to form fractions is using the suffix -nnes attached to the ordinal number stem: kolmannes (1/3), neljännes (1/4). Alternatively, compound words with -osa (part) are used: kolmasosa. When a cardinal number precedes a fraction (e.g., 2/3), the fraction takes the partitive singular: kaksi kolmannesta.

2. Decimals and Large Numbers
Finnish uses a comma (pilkku) as the decimal separator. Short decimals (1-2 digits) are often read as whole numbers (e.g., 5,20 = viisi pilkku kaksikymmentä), though digit-by-digit is also correct. For large numbers, use a non-breaking space as a thousands separator: 10 000.

3. The Concept of 'Half'

  • Puoli: Used for measurements and triggers the partitive singular: puoli litraa.
  • Puolitoista: A unique word for 'one and a half' that also takes the partitive: puolitoista tuntia.
  • Time: In telling the time, puoli indicates 30 minutes before the hour: puoli kahdeksan (7:30).
  • Puolet: A noun meaning 'the half', usually used with the elative case: Puolet kakusta (Half of the cake).

Examples (5)

  1. Söin vain kolmasosan kakusta.

    I only ate a third of the cake.

    Word by Word: I-ate only third-part-of cake-from.

    The fraction 'kolmasosa' is in the genitive case because it is the object of the action, and the cake is in the elative case (-sta).

  2. Kaksi kolmasosaa suomalaisista asuu kaupungeissa.

    Two-thirds of Finns live in cities.

    Word by Word: Two third-parts-of Finns-from live cities-in.

    When the numerator is higher than one, the fraction 'kolmasosa' must be in the partitive singular (kolmasosaa).

  3. Lämpötila on kolmekymmentäseitsemän pilkku viisi astetta.

    The temperature is thirty-seven point five degrees.

    Word by Word: Temperature is thirty-seven comma five degrees.

    Note the use of 'pilkku' (comma) for the decimal point.

  4. Tarvitsen puolitoista litraa maitoa.

    I need one and a half liters of milk.

    Word by Word: I-need half-second liter-partitive milk-partitive.

    'Puolitoista' (1.5) triggers the partitive singular on the unit 'litraa'.

  5. Puolet omenoista oli pilalla.

    Half of the apples were spoiled.

    Word by Word: Half apples-from were spoiled.

    'Puolet' is used here because we are referring to half of a specific group of items (apples).

Common Mistakes

  • Using a period instead of a comma for decimals.

    3.5 kiloa
    3,5 kiloa

    In Finnish, the decimal separator is always a comma (pilkku). A period (piste) is used for dates, while large numbers use a space as a thousands separator (e.g., 1 000 000).

  • Saying 'puoli viisi' for 5:30.

    Different MeaningKello on puoli viisi.
    Kello on puoli kuusi.

    'Kello on puoli viisi' is a good sentence, but it means 4:30. In time-telling, 'puoli' means half an hour before the next hour, so 5:30 is 'puoli kuusi'.

  • Using the genitive case for the 'of' part of a fraction.

    neljännes kakun
    neljännes kakusta

    After 'neljännes', a part of something takes the elative case (-sta/-stä): neljännes kakusta. A genitive phrase works only in the other order: kakun neljännes.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

Fractions and DecimalsLevel 4

Learn This First

To understand fractions and decimals, you first need a solid grasp of basic cardinal numbers (1-10) and ordinal numbers, as these form the linguistic basis for fractional terms like 'kolmasosa' (a third). Additionally, knowing how numbers govern the partitive case is essential for using these values in sentences.

Words in This Pattern

puolipuoli