This Application Problem is a part of the Lesson 21, Unit 2, Grade 3. Have students complete the problem in partners so that Partner 1 rounds to the nearest ten and Partner 2 rounds to the nearest hundred-it's a time-efficient way of having both estimates to compare with the actual answer. Gloria fills water balloons with 238 mL of water. How many milliliters of water are in two water balloons? Estimate to the nearest 10 mL and 100 mL. Which gives a closer estimate?