Grade 3 Number & Operations in Base Ten × 3.NBT.1. Use place value understanding to round whole numbers to the nearest 10 or 100. View all Grade 3 Number & Operations in Base Ten Standards. 3.NBT.1. Use place value understanding to round whole numbers to the nearest 10 or 100. ? × 3.NBT.2. Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction. View interactive math games for all Grade 3 Common Core Standards 3.NBT.2. Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction. ?