扇 + Number + 巴掌
巴掌 (bāzhang) means "a slap" or "palm of the hand." It is commonly used in the phrase 扇巴掌, meaning "to slap someone." For example, 扇了一巴掌 means "gave a slap."
妈妈生气了,在我屁股上扇了一巴掌。
Māma shēngqì le, zài wǒ pìgu shàng shān le yì bāzhang.
Mom got angry and slapped me on the behind.
他气得差点给对方一巴掌。
Tā qì de chàdiǎn gěi duìfāng yì bāzhang.
He was so angry he nearly slapped the other person.
那一巴掌打得又响又疼。
Nà yì bāzhang dǎ de yòu xiǎng yòu téng.
That slap was both loud and painful.