Counting by tens in Swahili: ten, twenty, thirty

Kumi, ishirini, thelathini… The rhythm of the tens in Swahili eventually becomes musical. At first, I stumbled over 30 and 80, but then I realized that after 20, everything aligns almost by itself, with a little magic connector: na.

The list of tens

Here are the standard forms from 10 to 90. You will quickly see the ending -ini reappear.

• 10: kumi
• 20: ishirini
• 30: thelathini
• 40: arobaini
• 50: hamsini
• 60: sitini
• 70: sabini
• 80: themanini
• 90: tisini

The regular pattern after 20

To form the intermediate numbers, you add the unit after the ten with na (“and”). No hyphen, no complicated agreement: just words separated by spaces.

• 21: ishirini na moja
• 23: ishirini na tatu
• 35: thelathini na tano
• 47: arobaini na saba
• 58: hamsini na nane
• 69: sitini na tisa
• 74: sabini na nne
• 88: themanini na nane
• 90: tisini (exactly, no need for na)

The same logic applies to the “teens”: 11 is said kumi na moja, 14 kumi na nne, etc. And 100 is called mia moja, but we stick to the same principle for 120: mia moja na ishirini.

Where do these forms come from?

Many tens in Swahili come from Arabic, reflecting centuries of exchange on the East African coast. The correspondences are easily recognizable: ishirini ← Arabic “ʿishrīn” (20), thelathini ← “thalāthīn” (30), arobaini ← “arbaʿīn” (40), hamsini ← “khamsīn” (50), sitini ← “sittīn” (60), sabini ← “sabʿīn” (70), themanini ← “thamānīn” (80), tisini ← “tisʿīn” (90). Swahili has integrated these forms and adapted them to its phonology and regular spelling.

The Arabic influence on the Swahili lexicon is well documented by the Encyclopædia Britannica, and the tens are a particularly clear example. Good news for learners: once the pattern is memorized, everything follows without surprises.

Common pitfalls

• Confusing 30 and 80. Mnemonic tip: thelathini contains “la” (like “tatu/three”), while themanini contains “ma” (think of “many/eight” if that helps… the key is to anchor a contrast).
• Forgetting na between the ten and the unit. Without “na”, “ishirini moja” does not exist; you need “ishirini na moja”.
• Use hyphens. We write separate words: “thelathini na tano”, never “thelathini-na-tano”.
• Over-articulate “th” in the English way. In practice, many speakers produce th as t]. Just say it simply, clearly, and keep the rhythm of the syllables.

My experience

I often mixed up thelathini (30) and themanini (80). One day, I got into the habit of tapping the syllables with my fingertips: the-la-thi-ni (4 beats) vs the-ma-ni-ni (also 4, but that central “ma” hits differently). My teacher also had me practice ascending and descending mini-series: 70, 80, 90, 80, 70… In two weeks, my ear adjusted and the confusion disappeared.

How to practice

Read the list out loud, then combine: 21, 22, 23… 31, 32… and so on. If you want a guided playground, the module Numbers from Discus offers dedicated sections (for example 21–100) with listening and short input exercises. You can open it here: features/numbers. Alternate listening → repetition → writing, and keep an eye on the regularity of the pattern “tens + na + units”.