Numbers is the ninth skill in the Welsh language tree. It has three lessons, and it contains the information to navigate the two Welsh numbering systems and how they mesh with plurals, as well as some basic math.

Grammar NotesEdit

Numbering SystemsEdit

Welsh has two numbering systems, one based on powers of ten (decimal) and one based on powers of twenty (vigesimal).

The decimal system is the simplest, as we are already use this system. For numbers bigger than ten, the form is x tens and y units i.e. un deg tri is "thirteen" (one ten three).

The vigesimal system is a little more complicated, but it the traditional system. The basic unit is twenty, but that isn't even the half of it. A lot of the system is based on idiomatic sayings, so it is a little less complicated to use a table for the numbers up until forty. Important things to note are that the first ten are the same as the decimal system and fifteen is used a base whenever it comes up:

Number Welsh Number Number Welsh Number
1 un 21 un ar hugain
2 dau/dwy 22 dau/dwy ar hugain
3 tri/tair 23 tri/tair ar hugain
4 pedwar/pedair 24 pedwar/pedair ar hugain
5 pump 25 pump ar hugain
6 chwech 26 chwech ar hugain
7 saith 27 saith ar hugain
8 wyth 28 wyth ar hugain
9 naw 29 naw ar hugain
10 deg 30 deg ar hugain
11 un ar ddeg 31 un ar ddeg ar hugain
12 deuddeg 32 deuddeg ar hugain
13 tri/tair ar ddeg 33 tri/tair ar ddeg ar hugain
14 pedwar/petair ar ddeg 34 pedwar/petair ar ddeg ar hugain
15 pymtheg 35 pymtheg ar hugain
16 un ar bymtheg 36 un ar bymtheg ar hugain
17 dau/dwy ar bymtheg 37 dau/dwy ar bymtheg ar hugain
18 tri/tair ar bymtheg 38 tri/tair ar bymtheg ar hugain
19 pedwar/petair ar bymtheg 39 pedwar/petair ar bymtheg ar hugain
20 ugain 40 deugain

Plurals with NumbersEdit

When you are using a number with a noun, the noun is not made into a plural, against all logic. The other way this can work (that is not usually permitted on Duolingo) is to use o and the plural form of the noun. So "two dogs" is either dau ci or dau o gŵn.


Lesson 1Edit

  • un = one
  • dau = two
  • tri = three
  • pedwar = four
  • pump = five
  • chwech = six
  • saith = seven
  • wyth = eight
  • naw = nine

Lesson 2Edit

  • deg = ten
  • un deg un = eleven
  • un deg dau = twelve
  • un deg pump = fifteen
  • tri deg pedwar = thirty-four
  • pedwar deg chwech = forty-six
  • saith deg tri = seventy-three
  • naw deg un = ninety-one
  • oed = year

Lesson 3Edit

  • adio = addition
  • tynnu = subtraction
  • lluosi = multiplication
  • rhannu = division
  • yn hafal i = equals
  • symiau = math


Duolingo Lesson:

Wikipedia article on this topic:

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