STAAR Math REMEMBER THIS
Prime Number
A whole number greater than 1 that has exactly two factors (1 and itself) [ex:3] [ 3's only factors are 3 and 1]
Two-line strategy
Add the opposite (subtraction becomes addition, opposite sign (+ to - or - to +)
Opposite (inverse) of subtraction
Addition
[Inequalities} If you divide or multiply by a negative number, you must...
FLIP the inequality sign
≥
Greater than or equal to, closed circle, shade to the right
1.205 [ place value of 0]
Hundredths place
Dividing Fractions
KCF[ keep, change, flip]: *keep* your first fraction the same, *change* division to multiplication, *flip* the second fraction (reciprocal), then multiply like normal
≤
Less than or equal to, closed circle, shade to the left
Adding Decimals
Make sure to line up decimals
Subtracting decimals
Make sure to line up decimals
Percent to decimal
Move decimal two places to left. (25% to .25)
Decimal to percent
Move decimal two places to right. (.25 to 25%)
Opposite (inverse) of division
Multiplication
Multiplying fractions
Multiply the numerators Multiply the denominators Simplify the answer
Mixed Number to Improper Fractions
Multiply whole number by denominator, add that value to the numerator-that is your new numerator, your old denominator is your new denominator.
Adding fractions
Must have common denominator, then add the numerators
Fraction less than 1
Numerator less than the denominator
Decimal to fraction
Place fraction bar under decimal, decimal = 1, any number after = 0
Percent to fraction
Place percent over 100, reduce
Multiplying or dividing integers
Same sign positive, different sign negative *cue song*
Things you MUST ask for on the test
Scratch paper, highlighter, notecard
Adding integers with different signs
Subtract and keep the sign of the bigger number
Opposite (inverse) of addition
Subtraction
First thing to do when you get your test
Tear out reference sheet and mark it up
1.35 [ place value of 3]
Tenths place
On the left side of the number line, the farther from zero you are...
The smaller your numbers get
3.478 [ place value of 8]
Thousandths place
Fraction to decimal
Top dog gets the house, divide
Fraction to percent
Top dog gets the house, move decimal two places to the right
Subtracting two numbers
Use the two-line strategy
Adding integers with the same sign
add the numbers and keep the sign
Opposite (inverse) of multiplication
division
Mixed Number to Improper Fraction Example
e.g. 2 4/7 denominator= 7 numerator = denominator x whole number + original numerator 7 x 2 + 4 = 18 Answer: 18/7
Subtracting Fractions
find a common denominator then subtract the numerator
>
greater than
<
less than
fraction greater than 1
numerator is greater than the denominator
(1/4)^3 (3 is the exponent)
(1/4) x (1/4) x (1/4)
-5 compared to -2
-5 is SMALLER (less than) than -2
1/10
0.10
1/5
0.20
¼
0.25
1/3
0.33 repeating
2/5
0.40
½
0.50
3/5
0.60
2/3
0.66 repeating
¾
0.75
4/5
0.80
5/5
1
Dividing Decimals
1. If there is a decimal in the dividend, you draw an arrow up and that is where your arrow will be in the quotient 2. If there is a decimal in the divisor, you must move the decimal to the right until it is at the end of the number. 3. You must move the decimal back the same amount of times in the dividend.
How to set up a proportion
1. Line = Line 2. Label your lines 3. Plug in what you know (look for 3 things to plug in) 4. Solve for unknown (x)
Multiplying decimals
1. Multiple numbers as if whole numbers. 2. Then count total number of decimal places in the factors and add them (Ex: 2.2 and 2.33 has three total decimal places) 3. Add the total number of Decimal places to product, counting left to right (Ex: 22*233 = 5126 --> 5.126 final answer)
3 ways to solve a proportion
1. Up/down and down/up 2. Left/ right and right/left 3. Cross multiply (butterfly method)
Percent means per....
100
2^5 (5 is the exponent)
2 x 2 x 2 x 2 x 2
