## Math Formulas

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### P

#### Perimeter of a rectangle

Formula = 2(L + B) or L + B + L + B.
Where,
L = length of the rectangle, and
B = the breadth of the rectangle.
Unit of measurement = unit, e.g cm

#### Perimeter of a Square

Formula = 4(a).
Where,
a = the length a side of the square.
Unit of measurement = unit, e.g cm

#### Positive number operations

Rule 1: ADDING TWO POSITIVE NUMBERS:
(+x) + (+y) = (addition of y to x)
Example: (+5) + (+3) = +8

Rule 2: ADDING A NEGATIVE NUMBER TO A POSITIVE NUMBER:
(+x) + (-y) = (subtraction of y from x)
Example 1: (+5) + (-3) = +2
Example 2: (+3) + (-5) = -2

Rule 3: ADDING A POSITIVE NUMBER TO A NEGATIVE NUMBER:
(-x) + (+y) = (subtraction of y from x)
Example 1: (-5) + (+3) = -2
Example 2: (-3) + (+5) = +2

Rule 4: MULTIPLYING TWO POSITIVE NUMBERS:
(+x) * (+y) = (a positive number)
Example: (+5) * (+3) = +15

Rule 5: MULTIPLYING TWO NEGATIVE NUMBERS:
(-x) * (-y) = (a positive number)
Example: (-5) * (-3) = +15

Rule 6: MULTIPLYING A NEGATIVE NUMBER with A POSITIVE NUMBER:
(+x) * (-y) = (a negative number)
Example 1: (+5) * (-3) = -15
Example 2: (+3) * (-5) = -15

Rule 7: SUBTRACTING A POSITIVE NUMBER FROM ANOTHER POSITIVE NUMBER:
(x) - = (a positive number, if x > y. But answer is negative if x < y)
Example 1: (+5) - (+3) = 2
Example 2: (3) - (5) = -2

Rule 8: SUBTRACTING A NEGATIVE NUMBER FROM ANOTHER NEGATIVE NUMBER:
(-x) - (-y) = (a positive number)
Example 1: (-5) - (-3) = +7
Example 2: (-3) - (-5) = +7