十多年 & 十年多

多 can be used to indicate a number in excess but 十多个 and 十个多 are different, because 多 means over a specified number, which can be an integer larger than 1 or a decimal between 0 and 1. 

• 十多个小时 means more than 10 hours, which could be 11, 12, 13 hours.
• 十个多小时 means more than 10 but less than 11 hours, which could be 10 hours and 10 minutes, 10 hours and 15 minutes, or 10 hours and 45 hours, etc. 

Please think about these two situations:

• If David has learned Chinese for 12 years, we can say: 他学中文十多年了。（In this case, we used the structure: Number + 多 + Measure word + noun.)
• If David has learned Chinese for 10 years and 2 months, we can say: 他学中文十年多了。 (In this case, we used the structure: Number  + Measure word + 多+ noun.)

Please fill in the blanks by using 多 structure based on the contexts: 

1. 她来中国____________了。（14 months）

• a. 十多个月 
• b. 十个月多

2. 这个蛋糕____________。（$ 8.5)

• a. 八块多
• b. 八多块

3. 我们班上有____________同学。（22 students)

• a. 20多个同学
• b. 20个多同学

Please rearrange the words and form new sentences:

1. 他的    五十     妈妈       岁      多      了 
• His mother is already more than fifty years old.
2. 块     这个     三千    包     多     钱 
• This bag is more than three thousand kuai.
3. 书     他的     写    两百  了  多 页    了 
• He has written already more than two hundred pages for his book.
4. 中国    历史    有    年     的     五千    多  
• China has more than five thousand years of history.