Hi Welcome to MooMooMath. Today we are going to talk about adding sign numbers. Here are our examples. 5 minus negative 3 equals 8, and negative 6 plus minus negative 4 equals negative two. Now let’s go over the rules. First you change to addition. Next you use the “Two Mark Rule” Finally you have changed the problem to addition so you use the rules that apply to addition which are if you have the same sign you add and different sign you subtract and take the sign of the larger. So let’s look at these problems in slow Mo. Here is the “Two Mark Rule” After the first integer I will make two marks. So the negative sign becomes positive and I have to make a second mark so negative three becomes positive 3. So let’s look at the second problem. =6 – - 4 = I don’t change the -6 but the negative sign becomes + and the 4 becomes -4. I then apply my rules of addition so it becomes -6 - -4 =-10 Here is our last example 8 - -5 = Use the two mark rule so it becomes 8+ 5= 13. Hope this video helps.
How to use the "two mark rule" when subtracting negative numbers
Rules for adding and subtracting negative numbers
How do you solve the problem -6 -4 ? In order to solve these subtraction problems with negative and positive numbers you actually add the opposite number. It sounds confusing but it is actually pretty easy.
1. Apply the "two mark rule" which simply means you put two marks after the first number.This changes the problem to addition, and changes the second number to it's opposite number.
2. Apply the rules of addition which are:
Same sign: add and keep the sign
Different signs: subtract and take the sign of "more"