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Math: Operations with Signed Numbers - Tutorial
Example 1:
Example 1: 2 + 7 = 9
When adding a positive number and a negative number, the sign of the sum will be the same as the number with the largest absolute value.
Example 2: - 6 + 14 = 8 or -7 + 3 = -4
Hint: Think of it as numbers on a number line.
For example, start with -6 and count 14 spaces to the right in a positive direction.
The number you land on will be a positive 8.
Example 3: -3 + (- 5) = - 8
When adding a negative number and a negative number, the sign of the sum will be negative.
Hint: The numbers are both negative and are moving in the same direction on the number line.
Example 4: + (+5) = 5 or -(-4) = 4
Double signed numbers can be replaced with positive signed numbers.
When multiplying a positive number and a positive number, the sign of the product will be positive.
Example 1: 3 x 6 = 18
When multiplying a positive number and a negative number, the sign of the product will be negative.
Example 2: - 6 x 3 = -18
When multiplying a negative number and a negative number, the sign of the product will be positive.
Example 3: -3 (-2) = 6
When subtracting a negative number from a negative number, the difference is negative.
Example 1: -9 - 3 = -12
When subtracting a smaller negative number from a larger positive number, the difference is positive.
Example 2: -4 + 8 = 4
Double signed numbers with the same sign can be replaced with a plus sign.
Example 3: - 2 - (- 9) = - 2 + 9 = 7
Double signed numbers that are opposites can be replaced with a minus sign.
Example 4: -4 + (-1) = - 4 -1 = -5 -5 - (+ 6) = -5 - 6 = -11
This section will cover the fundamentals and rules of signed numbers.
Adding Signed Numbers
Subtracting Signed Numbers
Multiplying Signed Numbers
Dividing Signed Numbers
When dividing two numbers with the same sign, the answer is positive.
Example 2:
When dividing two numbers with different signs, the answer is negative.
When multiplying a string of positive and negative numbers, count the total number of negatives.
If there is an even number of negative signs, the answer will be positive.
If there is an odd number of negatives, the answer will be negative.
Example 4: (-2)(3)(-3) = 18 (-2)(-3)(-3) = -18
When adding a positive number and a positive number, the sign of the sum will be positive. Remember, it is not necessary to put a plus sign in front of a positive number.
