Learning goals: Teacher Facing Identify the closest multiples of 10 and 100 for numbers within 1,000. Understand that rounding is a formal way to say which number a given number is closer to, and that number is often a multiple of 10 or 100. Understand the meaning of “the closest multiple of 10.” Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from 3.3 Wrapping Up Addition and Subtraction Within 1,000, Grade 3.