1a:
580 - (580 × .1) - 20
580 - (58) - 20
522 - 20
502
1b:
990 - (990 × .25) - 20
990 - (247.5) - 20
742.5 - 20
722.5
I'm not sure how to solve #2.
In the real world you are not going to have a calculator on you 24/7. Nor will you have a pencil or paper to do longhand. You need to know how to accurately estimate your answers in order to be successful.
41
X 4
=
164 that the answer using standard Algorithm
Answer: FALSE
Reason: The Discriminant determines how many or what are the nature of the roots. To get the Discriminant of a quadratic equation, find the square the value of 'b' subtracted to the product of 4, the value of 'a', and the value of 'c'.
<h2>D - b² - 4ac</h2>
hope this helps :)