Numbers Eleven to Ninety-Nine | Swahili Grammar

Standard Swahili builds eleven through nineteen as kumi na + unit and other two-digit numbers as multiple of ten + na + unit. Thus 14 is kumi na nne, and 34 is thelathini na nne. The word na literally has additive force: “thirty and four.”

The arithmetic is regular, but noun-class agreement still matters. The tens word remains unchanged, while a final unit from the agreeing set takes the form required by the counted noun: wanafunzi ishirini na watatu “twenty-three students,” but vitabu ishirini na vitatu “twenty-three books.”

Eleven through nineteen

Number	Swahili	Structure
11	kumi na moja	10 + 1
12	kumi na mbili	10 + 2
13	kumi na tatu	10 + 3
14	kumi na nne	10 + 4
15	kumi na tano	10 + 5
16	kumi na sita	10 + 6
17	kumi na saba	10 + 7
18	kumi na nane	10 + 8
19	kumi na tisa	10 + 9

These are the bare forms used in counting, calculations, dates, and labels. All three parts are written separately. There is no hyphen and na is not optional.

Kumi na saba jumlisha mbili ni kumi na tisa.

Seventeen plus two is nineteen.

Tarehe kumi na nne tutafungua maonyesho mapya.

On the fourteenth, we will open the new exhibition.

In a calculation, mbili is the bare number “two.” After tarehe, the date is conventionally read with a cardinal expression; it does not need the ordinal connector meaning “fourteenth.” See dates for month and year formats.

The multiples of ten

Number	Swahili	Spelling risk
10	kumi	not umi
20	ishirini	initial i-
30	thelathini	th in both relevant syllables
40	arobaini	standard arobaini
50	hamsini	initial h-
60	sitini	not sita kumi
70	sabini	not saba kumi
80	themanini	the-, not tema-
90	tisini	not tisa kumi

The words from twenty upward must be learned; Swahili does not construct “six tens” as English-like multiplication. They are invariable and do not take noun-class prefixes.

Basi lina viti arobaini, lakini abiria ni thelathini tu leo.

The bus has forty seats, but there are only thirty passengers today.

Class 8 viti does not create viarobaini. The number remains arobaini. The clause still shows class agreement elsewhere: class 5 basi controls li- in lina.

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Memorize the nine multiples of ten as complete words. To create another two-digit number, add na and the unit: hamsini na saba, not a translated “five tens seven.”

Building any number up to ninety-nine

The productive formula is:

TENS + na + UNITS

Number	Build	Finished expression
21	20 + 1	ishirini na moja
26	20 + 6	ishirini na sita
38	30 + 8	thelathini na nane
45	40 + 5	arobaini na tano
57	50 + 7	hamsini na saba
64	60 + 4	sitini na nne
79	70 + 9	sabini na tisa
82	80 + 2	themanini na mbili
93	90 + 3	tisini na tatu

In bare arithmetic, these final units stay in their citation form. When the number modifies a noun, agreement can change that last word.

Agreement survives inside a compound number

The tens word is invariable. Final one through five and eight belong to the agreeing set, so they reflect the class of the counted noun.

Head noun	Quantity	Agreement-bearing ending
wanafunzi (class 2)	wanafunzi ishirini na watatu	wa-tatu
magari (class 6)	magari arobaini na mawili	ma-wili
vitabu (class 8)	vitabu thelathini na vinne	vi-nne
nyumba (class 10)	nyumba hamsini na tano	zero + tano
wageni (class 2)	wageni kumi na wanane	wa-nane

Wanafunzi ishirini na wawili wamejiandikisha kwa kozi ya jioni.

Twenty-two students have enrolled in the evening course.

Tumepokea maombi thelathini na matano ya nafasi hizo.

We have received thirty-five applications for those positions.

In the first, ishirini stays unchanged, final -wili takes class 2 wa-, and the verb has class 2 wa-. In the second, class 6 maombi controls ma-tano. The larger number does not erase the head noun’s grammar.

Numbers ending in one use the singular member’s “one” form even though the total noun phrase is plural: watu ishirini na mmoja, miti ishirini na mmoja, vitabu ishirini na kimoja, magari ishirini na moja. The one-unit remainder is conceived as a single member added to the tens.

Kwenye ziara hiyo kulikuwa na washiriki ishirini na mmoja kutoka mikoa sita.

On that visit there were twenty-one participants from six regions.

This special final-one pattern must be learned; ordinary watu mmoja by itself is impossible because a quantity of one requires singular mtu mmoja.

Prices and schedules in real use

—Madaftari haya ni shilingi ngapi? —Moja ni shilingi themanini, na mawili ni shilingi mia moja sitini.

—How much are these notebooks? —One is eighty shillings, and two are one hundred sixty shillings.

The price themanini is bare. The answer moja counts one class 5 daftari, while mawili agrees with understood class 6 madaftari. Larger money amounts are covered in hundreds, thousands and millions.

—Basi la mwisho linaondoka saa ngapi? —Saa kumi na moja jioni.

—What time does the last bus leave? —At five in the evening.

East African clock hours are counted from roughly six o’clock. Saa kumi na moja jioni is 5:00 p.m., not 11:00 p.m. For an ordinary duration or a date, the same number words retain their mathematical value; the conversion belongs specifically to clock-hour expressions.

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Separate three tasks: build the additive number, apply concord only to an agreement-bearing final unit, and then—only for clock time—convert the East African hour from the six-o’clock starting point.

Register and digit reading

These forms are neutral in (informal) and (formal) Standard Swahili. In careful financial or legal speech, a speaker may give both words and digits to prevent mishearing. Telephone numbers and codes are normally read digit by digit using bare forms, not as a two-digit quantity: 24 in a room number may be mbili nne, while the number twenty-four is ishirini na nne.

Hear the tens block before the unit

Several number pairs contain the same basic words in opposite places. Thelathini na sita is 36, whereas sitini na tatu is 63. A short pause after the complete tens word helps listeners identify the structure, especially over a poor telephone connection.

Nimesema thelathini na sita, si sitini na tatu.

I said thirty-six, not sixty-three.

—Namba ya chumba ni ipi? —Ni arobaini na saba; tarakimu zake ni nne na saba.

—What is the room number? —It is forty-seven; its digits are four and seven.

The first answer treats 47 as a quantity and therefore uses arobaini na saba. The clarification reads the digits separately as nne na saba. In an amount, age, or total, do not switch casually to digit reading; in a reference code, telephone number, or room label, digit-by-digit reading may be the intended convention. Careful speakers repeat the whole number rather than trying to repair only its final syllable.

Common Mistakes

Omitting additive na

❌ Tiketi ni shilingi ishirini tano.

Incorrect — a nonzero unit after the tens requires na.

✅ Tiketi ni shilingi ishirini na tano.

The ticket costs twenty-five shillings.

Making the tens word agree

❌ Watu waishirini wanasubiri nje.

Incorrect — ishirini is invariable.

✅ Watu ishirini wanasubiri nje.

Twenty people are waiting outside.

Omitting agreement on the final unit

❌ Madaktari thelathini na mbili wamehudhuria semina.

Incorrect in careful Standard Swahili — the human final unit must be wawili.

✅ Madaktari thelathini na wawili wamehudhuria semina.

Thirty-two doctors have attended the seminar.

Constructing a multiple of ten word by word

❌ Bei imepanda hadi sita kumi.

Incorrect — sixty is the lexical form sitini.

✅ Bei imepanda hadi sitini.

The price has risen to sixty.

Reading the East African hour as a Western clock number

❌ Saa kumi na moja jioni ni saa kumi na moja baada ya adhuhuri kwa mfumo wa kimataifa.

Incorrect — East African saa kumi na moja jioni corresponds to 5 p.m., not 11 p.m.

✅ Saa kumi na moja jioni ni saa tano baada ya adhuhuri kwa mfumo wa kimataifa.

East African hour eleven in the evening is 5 p.m. on the international clock.

Key Takeaways

Learn kumi na... for 11–19 and the lexical multiples ishirini through tisini.
Build other two-digit numbers as tens + na + unit.
Tens are invariable, but final one through five and eight take appropriate concord when modifying a noun.
Bare calculations, dates, codes, and noun-modifying quantities do not all use the same surface form.

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