1. Multiplying Integers Word Problem

2. Integers Recap
Zero
Negative integers
Positive integers
The numbers –1, –2, –3, … (to the left of zero) are called negative integers
The numbers 1, 2, 3,… (to the right of zero) as positive integers.
The new set of numbers …, -3, -2, -1, 0, 1, 2, 3,… are called Integers.
‘–’ symbol in front of a number is read as 'negative' or 'minus'.
For example, –5 is read as negative 5 or minus 5.
A number without a sign is considered as a positive number.
For example, 5 is considered as +5.

3. Terminologies Positive Negative Above sea level Above ground Increase
Gain/Profit
Deposit
Positive Marking
Kept back
Raises
Below sea level
Below ground
Decrease
Loss
Withdraw
Negative Marking
Taken Out
Descends

4. + ( + ) = + + ( - ) = - - ( - ) = + - ( + ) = -
Rules of Addition and subtraction
Rule 1
Two numbers have same sign
Add the numbers
Copy bigger number sign
Rule 2
Two numbers have different sign
Subtract the numbers
Copy bigger number sign
Rules of multiplication
Converting 2 symbols into 1
Rule 1
Multiply same sign  Answer is +
+ ( + ) = +
- ( - ) = +
Rule 2
Multiply different sign Answer is –
+ ( - ) = -
- ( + ) = -

5. Example 1:On a mountain the temperature decreases by 5°c for every 10m ascent.
What will be the temperature 100m above point A. If the temp at A is 6°c.
Given: Temp at A = 6°c
Temp decreases by 5°c for every 10m ascent.
To find: Temp at 100m above point A
Solution:
Temperature decreases by - 5°c for every 10m for every 10 m = - 5°c temp drop
To reach 100m ,10 should be multiplied with 10 m m x 10 = - 5°c x 10 m
At 100m, temperature reduces by - 50°c
The temperature reduces by - 50°c above 100 m from point A
At point A the temperature was +6°c.
So, exact temp at 100m, above point A = = - 44 °c
The exact temperature above 100m from point A = - 44°c

6. Example 2: In a test containing 15 questions, 4 marks is given for correct answer and
-2 for wrong answer. Mohan attempted all the questions and only 9 of his answers
were correct. What was his test score?
Given: Total number of question = 15
No. of correct answers given by Mohan = 9
Mark for one correct answers = 4 (i.e. +4)
Mark for one wrong answers = -2
To find: Total marks scored by Mohan
Soln: Marks scored by Mohan on 9 correct answers = 9 x 4 = 36
Marks scored by Mohan on 6 (=15-9) wrong answers = 6 x -2 = -12
Test Score = Correct answers marks + Wrong answers marks
= 36 + (-12) = 36 – 12 = 24
By sign rule,
(+) x (+) = +
(+) x (-) = -
Answer: The test score is 24
By rule + (-) = -

7. Try these A company manufactures 16m of cloth every hour. After 7
hours it is seen that due to a worker's fault 7m of cloth is
spoiled. At present how many meters of cloth does the
company has for sale
A chocolate company earns a profit of Rs.8 per dark
chocolate and profit of Rs.5 per white chocolate. What is the
earnings if it sells 300 dark and 800 white chocolates in a month?