When adding two numbers with the same sign,
1. add the absolute values, and
2. write the sum (the answer) with the same sign as the numbers.

• (+4) + (+7) = +11
• (5) + (8) = 13
• (4) + (6) = 10 
When adding two numbers with different signs,
1. subtract the absolute values, and
2. write the difference (the answer) with the sign of the number having the larger absolute value.

• (+5) + (8) = 3
• (10) + (+15) = +5
• (20) + 17 = 3 
Subtracting Signed Numbers:
When subtracting two numbers, change the sign of the number being subtracted and then follow the rules for adding signed numbers. (Subtracting a number is adding its opposite.)

• 8  (3) = 8 + (+3) = 11
• 10  (8) = 10 + (+8) = 2
• 8  (+6) = 8 + (6) = 14
• 13  8 = 13 + (8) = 5 
Multiplying or Dividing Signed Numbers:
When multiplying or dividing two numbers,
• If the signs are the same, the result is positive.
• If the signs are different, the result is negative.
If you have a long series of multiplications of negative values, remove the negative signs in pairs.
(2)(3)(1)(1)(5)(1)(2) =(2)(3)(1)(1)(5)(1)(2) = 60

• (+3) x (+9) = +27
• (6) x (8) = +48
• (5) x (+6) = 30
• (+8) x (2) = 16
• (+12) ÷ (+3) = +4
• (15) ÷ (5) = +3
• (20) ÷ (+2) = 10
• (+18) ÷ (3) = 6
