This Problem Set is a part of the Lesson 12, Unit 1, Grade 5. In this lesson, students begin to use estimation to confirm the placement of decimals when finding products of decimal fractions. They explore with the area model that, when multiplying decimal fractions, students can multiply the numerals first and then think about the units to help place the decimals. Then they use estimation to confirm the placement of the decimal when finding the product of a whole number and a decimal fraction written to the tenths and hundredths place.