Numbers in Brithenig

1	yn	6	sei	11	ynniġ	16	yn e chindiġ
2	dew	7	seth	12	dewddiġ	17	dew e chinniġ
3	trui	8	oeth	13	truiddiġ	18	dewnoe
4	cathr	9	noe	14	cathorddiġ	19	cathr e chinniġ
5	cinc	10	deġ	15	kinniġ	20	gweint
21	yn e weint
30	deġ e weint	40	dew weint
50	deġ e ddew weint	60	trui weint
70	deġ e thrui weint	80	cathr gweint
90	deġ e chathr gweint	100	cent
1000	mil	1000000	milliwn
0	sero, rhen	.	puith

Numbers precede the noun being counted. Yn causes feminine nouns to soften; dew, trui and sei cause following nouns to undergo spirant mutation; other numbers come before nouns without causing mutation. When the noun following dew and trui is a feminine collective of a masculine noun (see above under nouns) then the noun undergoes soft mutation rather than spirant mutation.

Before a noun cinc, gweint and cent become cin, gwein and cen. The noun being counted is always singular.

Big numbers are put before nouns in two different ways:

yn of e chinniġ, sixteen men

yn e chinniġ di llo h-of, sixteen (of the) men

Ordinal numbers exist for one to ten:

1st	prif	6th	seist
2nd	segun	7th	sethif
3rd	terth	8th	oethif
4th	carth	9th	noef
5th	kint	10th	degif

In shorthand these are reduced to the number and the last two letters of the ordinal spelling.

'Once, twice, three times' are made with using the cardinal number with the noun gweġ: yn weġ, dew weġ, trui weġ, cathr gweġ.