HISTORICAL · DECIMAL WITH BINARY STEPS

Mangarevan

Spoken counting with groups of 10, 20, 40, and 80. The counting unit depends on the object.

Convert numbers
Place
Mangareva, Gambier Islands, French Polynesia
Period / variant
Traditional object-specific counting, documented in the 19th–20th centuries
EXAMPLES

40 · Decimal with binary steps

40 counting units = two paua = four takau.

Worked example

Read 40 in Mangarevan

First choose the counting unit. Then read any groups of 80, 40, 20, and 10, followed by the remaining units.

  1. tataua names 40. Count this group once.

Check

40 = 40 counting units

Sources and notation notes

One unit can contain one turtle, two fish, four coconuts, or eight octopuses. Multiply the counting-unit total by that quantity to find the number of objects.

Bender & Beller · Mangarevan invention of binary steps for easier calculation (2013)

Number-word dictionary

Number words are the signs in this tradition. This dictionary shows the documented words and their meanings, preserving the spelling used by the sources. Some words name whole groups or connect parts of a number.

ta’i
1
rua
2
toru
3
’a
4
rima
5
ono
6
’itu
7
varu
8
iva
9
takau
10 counting units
paua
20 counting units
tataua
40 counting units
varu
80 counting units in the grouping context
tauga
counting unit; its object quantity depends on the goods

How the words fit together

Express the count as multiples of 80, followed by at most one 40, one 20, one 10, and the remaining ones. The input counts tauga; choose how many objects each tauga contains before converting it to objects.

  1. Choose the counting unit: a turtle, a pair of fish, four coconuts, or eight octopuses.
  2. Read the largest part first: a number before varu multiplies 80. A single varu names 80.
  3. Then add any tataua (40), paua (20), and takau (10), each used once at most. Finish with the remaining 1–9 units.
  4. For example, toru varu paua takau toru is 3 × 80 + 20 + 10 + 3 = 273 counting units.

10 in Mangarevan

10 counting units; for fish counted in pairs, this represents 20 fish.

20 in Mangarevan

20 counting units = two takau. The basic unit still depends on the object.

40 in Mangarevan

40 counting units = two paua = four takau.

80 in Mangarevan

80 counting units = two tataua. In the unit range, varu also means eight; context distinguishes the meanings.

273 in Mangarevan

3 × 80 + 20 + 10 + 3 = 273 counting units; an example given in the research paper.

Supports 1–799 counting units using Bender and Beller’s documented construction. These spoken forms do not automatically count individual objects. The language also has an ordinary decimal system; historical accounts of specialized counting vary.

History

Bender and Beller’s 2013 analysis draws especially on Te Rangi Hiroa’s ethnography. The specialized system counted valued goods alongside an ordinary decimal system; it was not a universal replacement for decimal counting.

How to read it

Express the count as multiples of 80, followed by at most one 40, one 20, one 10, and the remaining ones. The input counts tauga; choose how many objects each tauga contains before converting it to objects.

  1. Choose the counting unit: a turtle, a pair of fish, four coconuts, or eight octopuses.
  2. Read the largest part first: a number before varu multiplies 80. A single varu names 80.
  3. Then add any tataua (40), paua (20), and takau (10), each used once at most. Finish with the remaining 1–9 units.
  4. For example, toru varu paua takau toru is 3 × 80 + 20 + 10 + 3 = 273 counting units.

Limits

Supports 1–799 counting units using Bender and Beller’s documented construction. These spoken forms do not automatically count individual objects. The language also has an ordinary decimal system; historical accounts of specialized counting vary.

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