Question

5. Edy and Mario are math teachers workingwith a group of students. They are trying toprepare for a lesson on decimals. Some oftheir students are struggling withthe following calculation:7.3.98How could Edy and Mario use thedistributive property as a way of helping thestudents to do the calculation without acalculator, and without using the traditionalmethod for multiplying decimal numbers?Show and explain how they could use the distributive property to do the calculation.

Answer 1

Rewrite the decimal as a sum of three numbers.

$3.98=3+0.9+0.08$

Multiply 7 to each of the addends.

$\begin{gathered} 7(3+0.9+0.08)=7(3)+7(0.9)+7(0.08) \\ =21+6.3+0.56 \end{gathered}$

Add the addends.

$21+6.3+0.56=27.86$

Therefore, (7)(3.98) is equal to 27.86.