Predict the result
Signed quantities need careful attention to direction, absolute value, and operation signs.
Represent twenty degrees below zero and a stock profit of 2500 dollars.

Set up the model
Below zero is a negative quantity.
A profit is a positive change in money.

Work the example
Use negative twenty for the temperature and positive twenty five hundred for the profit.
The signs describe the directions of the quantities.

Check the result
Now find the absolute value of negative nine.
Take eight seconds to think before the answer appears.
[Eight-second silent pause to work; the answer remains hidden.]
Its distance from zero is nine.

Interpret the result
Absolute value is nonnegative; zero also has absolute value zero.