How do you say once in a century Swahili?

There isn't a single, direct translation for "once in a century" in Swahili. However, you can express the idea in a few ways:

1. Using a time period:

* Mara moja kwa karne: This literally translates to "once per century."

* Mara moja kila miaka mia: This means "once every hundred years."

2. Using a metaphorical phrase:

* Kitu kinachotokea mara chache sana: This translates to "something that happens very rarely."

* Kitu ambacho hutokea kwa karne: This means "something that happens once in a century."

3. Using a phrase to emphasize the rarity:

* Kitu kisichotokea mara nyingi: This translates to "something that doesn't happen often."

* Kitu adimu sana: This means "something very rare."

The best translation will depend on the specific context and the desired level of formality.