\begin{definition}[Definition:Number Names/Welsh]
These are the names of the numbers in Welsh:
{{begin-axiom}}
{{axiom | n = 1
        | lc = '''un'''
}}
{{axiom | n = 2
        | lc = '''dau''', '''dwy'''
}}
{{axiom | n = 3
        | lc = '''toi''', '''tair'''
}}
{{axiom | n = 4
        | lc = '''pedwar''', '''pedair'''
}}
{{axiom | n = 5
        | lc = '''pump''' (or '''pum''')
}}
{{axiom | n = 6
        | lc = '''chwech''' (or '''chwe''')
}}
{{axiom | n = 7
        | lc = '''saith'''
}}
{{axiom | n = 8
        | lc = '''wyth'''
}}
{{axiom | n = 9
        | lc = '''naw'''
}}
{{axiom | n = 10
        | lc = '''deg'''
}}
{{axiom | n = 11
        | lc = '''un ar ddeg'''
}}
{{axiom | n = 12
        | lc = '''deuddeg'''
}}
{{axiom | n = 13
        | lc = '''toi ar ddeg''', '''tair ar ddeg'''
}}
{{axiom | n = 14
        | lc = '''pedwar ar ddeg''', '''pedair ar ddeg'''
}}
{{axiom | n = 15
        | lc = '''pymtheg'''
}}
{{axiom | n = 16
        | lc = '''un ar bymtheg'''
}}
{{axiom | n = 17
        | lc = '''dau ar bymtheg''', '''dwy ar bymtheg'''
}}
{{axiom | n = 18
        | lc = '''deunaw'''
}}
{{axiom | n = 19
        | lc = '''pedwar ar bymtheg''', '''pedair ar bymtheg'''
}}
{{axiom | n = 20
        | lc = '''ugain'''
}}
{{axiom | n = 30
        | lc = '''deg ar hugain'''
}}
{{axiom | n = 40
        | lc = '''dugain'''
}}
{{axiom | n = 50
        | lc = '''deg ar deugain''' or '''hanner cant'''
}}
{{axiom | n = 60
        | lc = '''trigain'''
}}
{{axiom | n = 70
        | lc = '''trigain a deg''' or '''deg ar thrigain'''
}}
{{axiom | n = 80
        | lc = '''pedwar ugain'''
}}
{{axiom | n = 90
        | lc = '''pedwar ugain a deg''' or '''deg a phedwar ugain'''
}}
{{axiom | n = 100
        | lc = '''cant'''
}}
{{end-axiom}}
The different forms for $2$, $3$, $4$ and their derivatives are for masculine and feminine.
The different forms for $5$ and $6$ are elisions for use in front of certain letters.
The different forms for $50$, $70$ and $90$ are separate ways of saying the numbers.
Note:
:there are no distinct words for $11$ and $12$, indicating that there has been less influence of duodecimal systems on Welsh
:there are clear indications of base $5$ and vigesimal influences as well as decimal
:the interesting forms for $18$ (expressed as $2 \times 9$) and $50$ (expressed both as $10 + 40$ and $\dfrac 1 2 \times 100$).
\end{definition}