S.A.T. MATH TESTING TACTICS

Tactic 12: Use your calculator

Use your calculator!

Well of course you’re planning on using your calculator to perform calculations quickly and accurately.

You can also use your calculator to solve problems that you don’t know how or are unsure of how to solve algebraically.

Example 12.1

If x2 = 2, what is the value of ?

A) 1 B) 1.5 C) D) E)

First, use your calculator to find an approximation for x.

Note: the more decimal places you use, the more accurate your final answer will be!

2 2

2 1.414

x

x

1 1x xx x

1 2 2 2 1.5 2 2

Example 12.1 (continued)

Next: Substitute your estimate in for x and evaluate.

1 11.414 1.414

1.414 1.414

1 1x xx x

1.414 .707 1.414 .707

(2.121)(.707)

1.499547

Look at your answer choices.Pick the best one. You could use your calculator to estimate each of the answers as well, if necessary.A)1

B) 1.5

C)

D)

E)

1 2

2 2

1.5 2 2

Example 12.2

If a and b are positive numbers, with a3 = 3 and a5 = 12b2, what is the ratio of a to b?

What are we actually looking for here?

3 3a 3 3 1.442a

a

b

5 212a b5 2(1.442) 12b

26.235 12b2.519583 b

.519583 b.721 b

1.4422

.721

a

b

2

Example 12.3

Simplify the following expression13

33

11.7321

1.73211.7321

1.7321 .5773

1.7321

1.1548

1.7321 .666705....

Remember this is an estimate! What would be a good “nice” guess?

2.6

3

2/3

A calculator estimate is no substitute for good old-fashioned algebra. If you KNOW how to work a problem, you should follow your instincts. However, using your calculator might help you find the answer to a problem you might otherwise have to skip.USE THIS TACTIC SPARINGLY!!!

S.A.T. MATH TESTING TACTICSTactic 13: Know When NOT to Use Your Calculator

WHAT? Didn’t you just tell me to use my calculator???

Well… Yes… BUT—

Don’t get in the habit of using your calculator on problems that you can solve easier and FASTER without one.

Example 13.1

John had $150. He used 85% of it to pay his electric bill and 5% of it on a gift for his mother. How much did he have left?

Notice: John used 85% +5% of his money = 90% of his money

He has 10% left.

10% of 150 is $15 15

Example 13.2

If , then x = ? A) 36 B) 38 C) 310 D) 325

E) 326

9 9 99 3 3 3x

Try to rewrite both sides of the equation using powers of 3 so we can use the laws of exponents to simplify.

9 9 9

2 9

9 3 3 3

3 3 3

x

x

2 103 3x

10

2

3

3x

83x