Unit 1 · Standard 6.NS.3
Multiply Decimals
Key Vocabulary Level 1 support
Picture first, then the word, then a plain-language meaning. Say each word out loud.
4 × 7 = 28, so the product is 28
Product
The answer when you multiply.
In 3.25, the decimal point separates 3 (ones) from 25 (tenths and hundredths)
Decimal point
The dot that splits the whole number from the part after it.
3.7 × 4.2: round to 4 × 4 = 16, so the exact answer should be near 16
Estimate
A close answer you get by rounding first.
In 0.36: the 3 is in the tenths place (0.3) and the 6 is in the hundredths place (0.06)
Place value
What a digit is worth based on where it sits in a number.
3.4 (1 place) × 2.6 (1 place) = 8.84 (2 places total)
Decimal places
How many digits come after the decimal point.
Key Ideas & Notes
- The station needs 4.5 meters of heat shielding that costs $12.60 per meter.
- Commander Diaz needs to calculate the total cost before submitting the supply order.
- What is the total cost of the shielding?
- Estimate each product by rounding, then sort: which products are GREATER than 20 and which are LESS than 20?
Think About It
- What two quantities are being multiplied?
- How many total decimal places do the two factors have?
- How can estimating help you check if your answer is reasonable?
My Notes
Guided Examples
Example 1
What is 3.4 × 2.6?
Solution: 34 × 26 = 884. There are 2 total decimal places (1 + 1), so place the decimal to get 8.84.
Answer: A. 8.84
Example 2
What is 0.7 × 1.5?
Solution: 7 × 15 = 105. There are 2 total decimal places (1 + 1), so place the decimal to get 1.05.
Answer: A. 1.05
Example 3
What is 5.3 × 4?
Solution: 53 × 4 = 212. There is 1 total decimal place, so place the decimal to get 21.2.
Answer: A. 21.2
Write About the Math The Writing Revolution
I can explain my work using the words product, decimal point, estimate, and decimal places.
1. Kernel Sentence subject + verb
Model: Decimal point is the dot that splits the whole number from the part after it.Punto decimal es el punto que separa el número entero de la parte que sigue.
Write a kernel sentence about decimal point. Use a subject and a verb.Escribe una oración base sobre punto decimal. Usa un sujeto y un verbo.
2. Sentence Expansion because · but · so
Kernel: Decimal point matters in mathPunto decimal importa en matemáticas
Expand the kernel three ways. Add a reason, a contrast, and a result.
Decimal point matters in math because ___.Punto decimal importa en matemáticas porque ___.
Decimal point matters in math, but ___.Punto decimal importa en matemáticas, pero ___.
Decimal point matters in math, so ___.Punto decimal importa en matemáticas, entonces ___.
3. Sentence Types 4 ways to write a math idea
Tell one true fact about decimal point.Di un hecho verdadero sobre decimal point.
Decimal point ___.
Ask a question about decimal point.Haz una pregunta sobre decimal point.
How does ___ ?¿Cómo ___ ?
Show excitement about decimal point.Muestra entusiasmo sobre decimal point.
Wow, ___ !¡Guau, ___ !
Tell a partner what to do with decimal point.Dile a un compañero qué hacer con decimal point.
First, ___ .Primero, ___ .
4. Explain Your Reasoning use a sentence starter
I counted ___ decimal places.Conté ___ lugares decimales.
The product is ___ because ___.El producto es ___ porque ___.
This happens in real life when ___.Esto pasa en la vida real cuando ___.
Try It
Solve on your own. Check the answer key when you are done.
1. Which estimate is closest to 4.8 × 3.2?
- 5 × 3 = 15
- 4 × 3 = 12
- 5 × 4 = 20
- 48 × 32 = 1,536
2. A car travels 55.5 miles per hour for 2.4 hours. How far does it go?
- 133.2 miles
- 13.32 miles
- 1,332 miles
- 57.9 miles
Stretch Your Thinking Level 2 enrichment
Challenge task — explain your reasoning in full sentences.
A family buys 3.5 pounds of deli meat at $6.80 per pound. Show how to find the total cost. Use estimation to check if your answer is reasonable.
Sentence starter: The total cost is $___ because 3.5 × $6.80 = ___. I can estimate: ___ × ___ = ___, which is close to my exact answer, so it is reasonable.
Reflect — Exit Ticket
What is 4.6 × 2.3?
- 10.58
- 105.8
- 1.058
- 10.48
Answer Key & Teacher Guide
- Try It 1: A. 5 × 3 = 15 — Round 4.8 to 5 and 3.2 to 3. The estimate 5 × 3 = 15 is closest to the exact answer 15.36.
- Try It 2: A. 133.2 miles — 555 × 24 = 13,320. Total decimal places: 1 + 1 = 2. Answer: 133.20 = 133.2 miles.
- Exit Ticket: A. 10.58 — 46 × 23 = 1,058. There are 2 total decimal places (1 + 1), so the answer is 10.58.
Writing (TWR) — what to look for
- Kernel sentence: A complete sentence needs a subject and a verb. Example: Decimal point is the dot that splits the whole number from the part after it.
- Expansion: because gives a reason, but shows a contrast or exception, so shows a result. Answers vary; each must keep the kernel idea and add the correct kind of detail.
- Sentence types: Statement ends with a period, question with "?", exclamation with "!", and a command starts with an action verb (a "bossy" verb).