Question

2) Evaluate 9 X 364 – 9 X 125 – 9 X 39 without the use of your calculator

Answer 1

Answer:

9*364 - 9*125 - 9*39 = 1,800

Step-by-step explanation:

Mental Calculation

If we detect known patterns in the calculations, we could easily give their results without the use of calculators.

We are given the expression to evaluate:

9*364 - 9*125 - 9*39

The first thing to note is the 9 is a common factor of all terms, thus we take it out:

9*(364 - 125 - 39)

The negative numbers can be easily added

     125

+     39

------------

     164

Now our expression is much easier:

9*(364 - 164)

The subtraction of 364-164 is 200, thus the result of the operations is:

9*200. We only need to recall 9*2=18 and add two zeros to get 1,800, thus:

9*364 - 9*125 - 9*39 = 1,800