unit 3.3: adding and subtracting decimals
In Units 3.1 and 3.2, you learn the types of decimals, and how they compare to one another. Remember: Every decimal can be converted to fraction, and every fraction can be converted into a decimal!
Now, let's talk about the adding and subtracting of decimals. In the notes, you will see that adding and subtracting decimals is no different from adding and subtracting integers. To give you a head start, allow me to give you the following points:
Now, let's talk about the adding and subtracting of decimals. In the notes, you will see that adding and subtracting decimals is no different from adding and subtracting integers. To give you a head start, allow me to give you the following points:
- Use "BENCHMARKS" to estimate the answer. This will serve you as a guide. The definition of benchmarks is included in the notes.
- Adding and subtracting of decimals is exactly like the adding and subtracting of integers: It is done from right to left. The ONLY difference (and it is a very important one!) is that THE DECIMAL POINTS (PERIODS) must be lined up, so that they go on top of one another.
- Once you have lined up the decimal points, and have written the numbers in top of one another, proceed as you would if dealing with integers.
- At the end, make sure you bring the decimal point to the answer by putting it exactly where it was lined up.
7e_unit_3.3.pdf | |
File Size: | 3907 kb |
File Type: |
useful Videos
Before I give you some worksheets for practice, let's check out the following videos. They explain (and reinforce) what we talked about in class:
IMPORTANT: The following video contains information about all other operations with decimals besides adding and subtracting. So, in order to minimize the possibility of confusion, make sure you stop the following video at 3:40 minutes.
and what do you know?... there are songs to helps us remember!
online challenge review activities
Ready to challenge yourself? Try the following activities online:
And those dreaded word problems? Well... They are very important to be able to do. So, don't be scared... and try this activity:
worksheets (and answers)
To practice what you have learned so fat, I gathered the following worksheets. I promise you: Even though it seems like a lot of work, it actually is easy and fast to do. Try them, and then compare your answers to the ones I included here. Good luck!
7e_unit_3.3_worksheets.pdf | |
File Size: | 3802 kb |
File Type: |
Now, here are the answers to the worksheets. How did you do? Let me know if you have any questions.
7e_unit_3.3_worksheets_answers.pdf | |
File Size: | 4481 kb |
File Type: |
extra practice
Hopefully by now, you have a very good understanding of how to add and subtract decimals. But, as I said at the beginning of the year, the more we practice, the better off we are. So, with that in mind, I suggest you try (time allowing, of course!) the following exercises on your TEXTBOOK:
- Page 98: #1, 3 and 4
- Page 99: #5, 7, 8 and 12