L6 · Multiply/divide problem solving (including money)
“I can read a problem, choose multiply or divide (sometimes both, in steps), solve it, and interpret the answer in context - keeping a decimal answer when the thing can be split, and rounding up when the context needs whole containers.”
A class buys 6 packs of markers at $3.75 per pack and one storage box for $8.50. What is the total cost? Step 1: Read for the steps. '6 packs at $3.75 per pack' is a multiplication - equal groups. The box is a single extra amount - an addition at the end. Step 2: Multiply first. Use the place-value chart for 3.75 (3 ones, 7 tenths, 5 hundredths): 6 x $3.75 = $22.50. Step 3: Add the single item: $22.50 + $8.50 = $31.00. Step 4: Check with an estimate: 6 x $4 = $24, plus about $9, is about $33 - $31.00 sits close to the estimate on the number line, so it is reasonable.
Why do we multiply 6 x $3.75 BEFORE adding $8.50?
Five notebooks cost $2.40 each, plus one pen for $3.00. Total? -> 5 x $2.40 = $12.00; $12.00 + $3.00 = $15.00
"8 x $4.25 = ___. Then add a $6.00 case: ___ + $6.00 = ___." -> $34.00; $34.00; $40.00
10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.