**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**