1.1.3 Mathematical Operations

Negative Numbers:

Any numbers less than zero and have a negative or minus sign \( (−) \) in front of them are negative numbers.

Numbers greater than zero are referred to as positive numbers. If there is no sign in front of the number the number is positive.

Number Line:

Negative numbers are on the left side of zero whereas positive numbers are on the right.

Working with negative numbers:

• Adding/subtracting:
  • Adding a negative number in a positive number is same as subtracting the positive number

e.g. \( 5+ (-3)=5-3=2 \)

• While adding two negative numbers, add absolute value of each number and put a negative sign in front, and you will get the answer

e.g. \( (-5)+ (-3)=-5-3=-8 \)

• Subtracting a negative number from a positive number is same as adding two positive numbers

e.g. \( 5- (-3)=5+3=8 \)

• While subtracting a negative number from another negative number you are actually adding a positive number into a negative number

e.g. \( -5- (-3)=-5+3=-2 \)

• Multiplication/Division
  • Two numbers with the same sign changes into a positive number

e.g. \( (-10) \times (-2)=20 \) and \( 10 \times 2=20 \)

OR

\( (-10) \div (-2)=5 \) and \( 10 \div2=5 \)

• Two numbers with the different sign changes into a negative number

e.g. \( (-10) \times 2=-20 \) and \( 10 \times (-2)=-20 \)

OR

\( (-10) \div 2=-5 \) and \( 10 \div (-2)= -5 \)