Add and Subtract Decimals
Name Period
Objectives / Objetivos
Content Objective: I can add and subtract decimals by lining up the place values and the decimal points.
Language Objective: I can explain my steps using the words decimal, place value, tenths, hundredths, and add zeros.
Key Idea / Idea clave
Adding & Subtracting Decimals. 1. Line up the decimal points vertically by place value. 2. Insert placeholder zeros so each number has the same number of decimal digits. 3. Add or subtract right-to-left, regrouping as needed, and drop decimal straight down
I Notice / Observo
- What is the starting fuel amount?
- Which operation adds fuel and which removes fuel?
I Wonder / Me pregunto
- Why is it important to line up the decimal points?
Vocabulary / Vocabulario
| Term / Término | Definition / Definición |
|---|---|
| Add and Subtract Decimals Sumar y restar decimales | Combine or find the difference between decimals by lining up equal place values. Combinar o hallar la diferencia entre decimales alineando valores posicionales iguales. |
| Decimal Decimal | A number with a dot, like 0.5, that shows a part less than one. Un número con un punto, como 0.5, que muestra una parte menor que uno. |
| Place value Valor posicional | What a digit is worth based on where it sits in a number. Lo que vale un dígito según el lugar que ocupa en el número. |
| Tenths Décimas | The first spot after the decimal point. It shows parts out of 10. El primer lugar después del punto decimal. Muestra partes de 10. |
| Hundredths Centésimas | The second spot after the decimal point. It shows parts out of 100. El segundo lugar después del punto decimal. Muestra partes de 100. |
| Annex zeros Agregar ceros | Adding zeros at the end of a decimal so numbers line up evenly. Agregar ceros al final de un decimal para que los números se alineen. |
Practice Preview / Vista previa de práctica
Read each task. Show your work in the spaces provided and explain how you know.
1. What is 14.6 + 3.85?
- A 17.45
- B 18.35
- C 18.45
- D 18.55
Answer:
2. Compute each decimal sum or difference.
Complete each empty cell. Show your reasoning below.
| Problem | Answer |
|---|---|
| 5.63 + 2.7 | |
| 12.4 − 8.56 | |
| 9.08 + 4.925 | |
| 25.1 − 13.47 | |
| 7.006 + 3.94 |
3. Round each number to the nearest whole number to estimate the sum or difference. If the estimate equals 10, calculate the exact result before sorting. Sort by whether the actual result is greater than or less than 10.
Write each item in its correct group.
4. Find Tasha's Mistake
Which step has the mistake, and what should it be?
Reflection / Reflexión
One thing I learned today / Una cosa que aprendí hoy: