There's something about numbers that is so difficult to nail, especially in another language. For this reason, it is important to devote special attention to: 

• Days, Months, Years

• Numbers (count by tens, hundreds, thousands, etc.) 

• Ordinals (1st, 2nd, 3rd, 4th) 

• Read decimals and prices

• Read percents and statistics

• Know basic mathmatical expressions and symbols 

• Know words that imply number (duplicate, pair, couple, etc).

• Understand how partitives function gramatically