块 (kuài)

Definition: Used for pieces or lumps, also for currency (money).

Examples:

我要一块蛋糕。

Wǒ yào yī kuài dàngāo.

(I want a piece of cake.)

这块表很贵。

Zhè kuài biǎo hěn guì.

(This watch is very expensive.)

我有十块钱。

Wǒ yǒu shí kuài qián.

(I have ten yuan.)