Adding and Subtracting Integers Using a Number Line
First we learned that -8 - 7 = -8 + -7 -if you switch the sign from a subtraction to an addition problem, then you must change the sign of the second number from a positive number to a negative number.
if the problem is -3+4 you start at zero move to the left 3 so you are into the negatives then when adding 4 you go up 4 to the right and see where that puts you. Which is at 1.
- If you are doing a subtraction problem on a number line you place the two numbers in their correct place and starting from the second number draw an arrow towards the first number. Find the distance between the two and that is the answer, if the arrow is pointing towards the right its a positive number and if the arrow is pointing to the left it's a negative number.
5 x 2
if the problem is -5 X 2 then you still do 5 hops of two except you make the hops on the negative side of the number line but hte arrow points to the right.
If it is 5 x -2 it's the same thing as the problem explained above but the arrow points to the left.
Multiplication using Chips
3 x -2 =? This means three sets of negative two
-2 x 3
If you have 6 positive and 6 negative chips you are then able to take out two groups of 3. the answer is then -6
The same thing occurs when the problem is -2 x -3 =? you have six positive and six negative chips and then take out two groups of -3 and the answer is positive 6.
Very helpful blog! I really like your example of doing multiplication on a number line. This is a method that I wasn't introduced to until this class, and certainly would have helped me when I was learning multiplication. Nicely done!
ReplyDeleteI like how you started off with the changing the sign concept because I didn't see that on the other blogs I looked at. Your examples are very clear and easy to understand. I particularly liked your multiplication example and loved how it was colored for positive and negative.
ReplyDeleteGood job with your blog for this week. Your adding on a number line explanation and picture is great. I like your multiplication using chips picture and explanations, because I know that I had a little bit of difficulties doing this in class, and your explanation made a lot more sense. Your multiplying on a number line visual and explanation was easy to read and understand as well. Over all, great job!
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