📚 Topic Summary
Adding decimals in tenths is similar to adding whole numbers, but you need to line up the decimal points. This ensures you're adding tenths to tenths and ones to ones. For example, to add $3.2 + 1.5$, you would write them vertically, aligning the decimal points, and then add each column just like you would with whole numbers. The decimal point in the answer should be in the same column as the decimal points in the numbers you're adding.
Let's try another one. When you add $4.8 + 2.1$, align the decimal points, add the tenths ($8 + 1 = 9$), and add the ones ($4 + 2 = 6$). The result is $6.9$. Practice makes perfect, so let's dive into some exercises!
🧮 Part A: Vocabulary
Match the term with its definition:
| Term |
Definition |
| 1. Decimal |
A. The point separating the whole number from the fraction. |
| 2. Tenth |
B. One part of ten equal parts. |
| 3. Sum |
C. The result of adding two or more numbers. |
| 4. Addition |
D. The process of combining numbers. |
| 5. Place Value |
E. The value of a digit based on its position in a number. |
Match them up! (Answers: 1-A, 2-B, 3-C, 4-D, 5-E)
✍️ Part B: Fill in the Blanks
Complete the sentences below:
When adding decimals, it's important to ________ the decimal points. The result of adding two numbers is called the ________. A tenth is one part of ________ equal parts. The ________ separates the whole number from the fraction. ________ is the process of combining numbers.
(Answers: align, sum, ten, decimal point, Addition)
🤔 Part C: Critical Thinking
Explain, in your own words, why it is important to align the decimal points when adding decimals. What happens if you don't align them?