Here's how to say and write the numbers from 11 to 100 in Mandarin. It’s easy if you follow these simple steps:

1. Numbers 11 to 19:

• 11: 十一 (shí yī)
• 12: 十二 (shí èr)
• 13: 十三 (shí sān)
• 14: 十四 (shí sì)
• 15: 十五 (shí wǔ)
• 16: 十六 (shí liù)
• 17: 十七 (shí qī)
• 18: 十八 (shí bā)
• 19: 十九 (shí jiǔ)

2. Tens (20 to 90):

• 20: 二十 (èr shí)
• 30: 三十 (sān shí)
• 40: 四十 (sì shí)
• 50: 五十 (wǔ shí)
• 60: 六十 (liù shí)
• 70: 七十 (qī shí)
• 80: 八十 (bā shí)
• 90: 九十 (jiǔ shí)

3. Numbers 21 to 99: Just put the tens and units together.

For example:

• 21: 二十一 (èr shí yī)
• 45: 四十五 (sì shí wǔ)

By following these steps, you'll be able to use Mandarin numbers in your everyday life with ease!