Signed numbers are used to represent increases and decreases in real-world situations. Increases such as weight gain, account deposits, or heights above sea level are represented by positive numbers, while decreases like weight loss, withdrawals, or temperatures below zero are represented by negative numbers. An example involves a submarine that was initially 300 meters under sea level at 10:00. Over the next few hours it descended 148 meters and ascended 103 meters. To calculate its depth at 15:00, its initial depth is added to the total descent and ascent amounts, yielding a depth of 345 meters under sea level.

1. Real-life Scenario on Signed numbers
By Mohamad El Kobrosly

2. Signed numbers are used in real world situations. For example, increase in
weight, deposit in an account, increase in pay, income, profit, investment,
height above sea level, etc. are represented by positive signed numbers.
Decrease in weight, withdrawal from an account, pay cut, loans, liabilities,
losses, temperature below zero, position below sea level, etc. are represented
by negative signed numbers.
What are Signed Number?

3. Rules for writing signed numbers in real world
situations
Increases are often written as positive signed numbers (+).
Decreases are often written as negative signed numbers (-).

4. Let us have an example on signed
numbers in real life

5. At 10:00, the position of a submarine is 300 m under
sea level. Its changes in depth were recorded every
hour in the table. What is the depth of the submarine
at 15:00?

6. Let us analyze our problem
Under sea level = - -300m (Given at 10:00)
Descended means= - Total of Descending = -53 + (-31) + (-64) = -148m
Ascended means = + Total of Ascending = +18 + (+85) = 103m
The depth of the submarine at 15:00 =
Under sea level + Descended + Ascended
-300 + (-148) + (+103) =
-448 + (+103) = - 345
The depth of the submarine at 15:00 is 345m under sea level

7. Thank you