Math Magic
Tuesday, February 15, 2011 at 5:00AM
We have a great little book in our house: Money Math Magic by David Ginn. As I've mentioned before, I'm trying to make math more fun and interesting for my nine year old, and for my six year old I'm just trying to keep up with him by providing challenges in math. We did this activity in about 5 minutes, but then I let my oldest practice several times (she wants to show it to her piano teacher at lessons today --- so I think I succeeded with this activity! Yay!)
Have fun with this!
1. Use a piece of paper to write down the number "1089". After you write down the number, ball it up and place it on the floor.
2. Tell your friend to write down any three digit number with different digits(on a second sheet of paper).
3. Tell your friend to reverse the digits.For example, 742 is reversed to 247. Next, tell your friend to subtract the bigger number and the smaller number.
4. Tell your friend to reverse the answer he just got. After that, your friend should add up the last two digits.
Here's what ours looked like:
5. Your friend should come up with a total of 1089. Ask your friend the answer he/she got. When he/she tells you the answer, grab the piece of paper that you had on the floor. Unball the piece of paper and show your friend.
6. Your friend will be amazed!
7. Examples: A. 753 - 357 = 396 B. 396 + 693 = 1089 A. 846 - 648 = 198 B. 198 + 891 = 1089 As you can see, the answer will always be 1089
*No matter what three digit number your friend uses, as long as the digits are ALL DIFFERENT, the answer will always be 1089. However, if the third number has only two digits (the number 495 in my example), your friend must add a zero to its left to make it three digits. If the remainder was, for example, 99, you have to put a zero in front, making it 099.
This post is linked to the Hip Homeschool Hop - hope you find some good ideas hopping around to other homeschoolers' blogs today!
