Cheat sheet

Digital SAT Math Cheat Sheet

Algebra

35%of exam

Linear EquationsSystemsInequalitiesSlope & Intercepts

Advanced Math

35%of exam

QuadraticsExponentialsPolynomialsFunction Transformations

Problem-Solving & Data Analysis

15%of exam

Ratios & RatesPercentagesStatisticsScatterplots

Geometry & Trigonometry

15%of exam

Area & VolumeTrianglesCirclesTrig Ratios

Quick Facts

Exam
Digital SAT Math
Owner
College Board
Questions
44 (2x22)
Time
70 min (35/module)
Score range
200-800
Calculator
Allowed throughout (Desmos)
Format
75% MC, 25% grid-in
Level
High school / college admissions
Blueprint
Digital SAT since March 2024

Order of Operations

PEMDAS: Parentheses, Exponents, Multiply/Divide, Add/Subtract

P: Parentheses firstE: Exponents nextMD: left to rightAS: left to right

Slope vs Y-Intercept

Slope

  • Rate of change
  • Rise over run

Y-intercept

  • Starting value
  • Where line crosses y-axis

Steepness vs starting point

Problem Approach Picker

  1. Two linear equations givenSubstitution or elimination(Systems)
  2. Equation has x²Quadratic formula or factor(Advanced Math)
  3. Ratio or rate givenSet up proportion(PSDA)
  4. Percent change asked(new-old)/old(PSDA)
  5. Right triangle sidesPythagorean theorem(Geometry)
  6. Angle and one side knownSOH-CAH-TOA(Trig)

Linear Equations & Slope

Slope formula
(y2-y1)/(x2-x1)
Slope-intercept form
y=mx+b
Point-slope form
y-y1=m(x-x1)
Standard form
Ax+By=C
Parallel lines
Equal slopes
Perpendicular lines
Negative reciprocal slopes
x-intercept
Set y=0
y-intercept
Set x=0

Systems & Inequalities

Substitution method
Solve one, sub in
Elimination method
Add or subtract equations
No solution
Same slope, different intercept
Infinite solutions
Equations are identical
One solution
Different slopes
Flip inequality sign
Multiply or divide by negative
Compound inequality
Two bounds, one variable
Absolute value equation
x=a or x=-a

FOIL for Binomial Multiplication

First, Outer, Inner, Last term products

First: multiply first termsOuter: multiply outer termsInner: multiply inner termsLast: multiply last terms

Factoring vs Quadratic Formula

Factoring

  • Fast for nice numbers
  • Whole-number roots

Quadratic formula

  • Always works
  • Handles messy roots

Try factor first

Function & Graph Picker

  1. Need vertex of parabola-b/2a for x
  2. Need number of rootsCheck discriminant
  3. Growth over timeExponential model
  4. Need x-interceptsFactor or quadratic formula
  5. Graph shifts up/downAdd constant outside f(x)
  6. Graph shifts left/rightAdd constant inside f(x)

Quadratics

Standard quadratic form
ax²+bx+c=0
Quadratic formula
x=(-b±√(b²-4ac))/2a
Discriminant formula
b²-4ac
Discriminant > 0
Two real roots
Discriminant = 0
One repeated root
Discriminant < 0
No real roots
Vertex form
a(x-h)²+k
Vertex x-coordinate
-b/2a
Factoring trinomials
Find two binomial factors
Completing the square
Convert to vertex form

Exponential vs Linear Growth

Linear growth

  • Adds constant amount
  • Straight-line graph

Exponential growth

  • Multiplies by factor
  • Curved graph

Add vs multiply

Exponents & Transformations

Exponential growth
a(1+r)^t
Exponential decay
a(1-r)^t
x^a · x^b
Add exponents
x^a ÷ x^b
Subtract exponents
(x^a)^b
Multiply exponents
x^-a
1/x^a
x^0
Equals 1
x^(1/n)
nth root of x
f(x)+k
Shifts graph up k
f(x-h)
Shifts graph right h

Polynomials & Radicals

Difference of squares
a²-b²=(a+b)(a-b)
(a+b)²
a²+2ab+b²
(a-b)²
a²-2ab+b²
a³+b³
(a+b)(a²-ab+b²)
Radical equations
Check for extraneous roots
√(x²)
Equals |x|
Polynomial degree
Highest exponent value
End behavior
Determined by leading term

Mean vs Median

Mean

  • Average of all values
  • Skewed by outliers

Median

  • Middle value sorted
  • Resistant to outliers

Outliers affect mean more

Data & Geometry Picker

  1. Two categorical variablesTwo-way frequency table
  2. Trend between two variablesScatterplot and line of fit
  3. Spread of data askedStandard deviation or IQR
  4. Missing side, right trianglePythagorean or trig ratio
  5. Angle in radiansConvert using π/180
  6. Circle arc lengthUse radius and central angle

Ratios, Rates & Percentages

Unit rate
Ratio per one unit
Percent increase
(new-old)/old×100
Percent decrease
(old-new)/old×100
x% of n
(x/100)×n
Direct variation
y=kx
Inverse variation
y=k/x
Cross multiplication
a/b=c/d→ad=bc

Statistics & Data Interpretation

Mean
Sum divided by count
Median
Middle value when sorted
Mode
Most frequent value
Range
Maximum minus minimum
Standard deviation
Spread of data around mean
IQR
Q3 minus Q1
Scatterplot association
Positive, negative, or none
Line of best fit
Models the overall trend
Margin of error
Range of sampling uncertainty
Two-way table
Joint and marginal frequencies

SOH-CAH-TOA Trig Ratios

SOH sin, CAH cos, TOA tan

SOH: opposite over hypotenuseCAH: adjacent over hypotenuseTOA: opposite over adjacent

Area vs Perimeter

Area

  • Space inside shape
  • Squared units

Perimeter

  • Distance around shape
  • Linear units

Inside vs boundary

Area & Volume Formulas

Circle area
πr²
Circumference
2πr
Triangle area
½×base×height
Rectangle area
length×width
Trapezoid area
½(b1+b2)×height
Cylinder volume
πr²h
Sphere volume
(4/3)πr³
Cone volume
⅓πr²h
Prism volume
length×width×height

Common Pythagorean Triples

3-4-5, 5-12-13, 8-15-17 scale to any multiple

3-4-5 triangle5-12-13 triangle8-15-17 triangle6-8-10 also works

Sine vs Cosine

Sine

  • Opposite over hypotenuse
  • Rises from 0

Cosine

  • Adjacent over hypotenuse
  • Starts at maximum

Opposite vs adjacent side

Triangles & Trigonometry

Pythagorean theorem
a²+b²=c²
3-4-5 triple
Common right triangle
5-12-13 triple
Common right triangle
45-45-90 triangle
Legs x, hyp x√2
30-60-90 triangle
Sides x, x√3, 2x
SOH-CAH-TOA
sin cos tan ratios
sin θ
Opposite ÷ hypotenuse
cos θ
Adjacent ÷ hypotenuse
tan θ
Opposite ÷ adjacent
Triangle angle sum
180 degrees total
Similar triangles
Proportional sides, equal angles

Special Right Triangle Ratios

Two special right triangles to memorize

45-45-90: legs x, hyp x√230-60-90: sides x, x√3, 2xMemorize both ratio setsFaster than trig on these

Common Traps

Percent Change Base Trap

Always divide by original value Not the new value

Vertex Form Hidden Sign

(x+3)² means h = -3 Flip sign to find h

Radians vs Degrees Trap

π radians equals 180 degrees Watch calculator angle mode

Squaring Creates Extraneous Roots

Check answers in original equation Squaring can add fake roots

Area vs Perimeter Units

Area is squared units Perimeter is a single length

Mean vs Median Skew

Outliers pull the mean Median ignores extreme values

x-intercept vs y-intercept

x-intercept sets y to zero y-intercept sets x to zero

Last Minute

  1. 1.44 questions across two modules
  2. 2.70 minutes total, 35 per module
  3. 3.Calculator allowed on every question
  4. 4.Desmos graphing calculator built in
  5. 5.Algebra & Advanced Math: 35% each
  6. 6.Geometry & Data domains: 15% each
  7. 7.Score range is 200 to 800
  8. 8.75% multiple choice, 25% grid-in
  9. 9.Module 1 routes to Module 2
  10. 10.Vertex x = -b/(2a)
  11. 11.Check for extraneous radical roots
  12. 12.Know triples: 3-4-5 and 5-12-13
  13. 13.SOH-CAH-TOA gives sin cos tan
  14. 14.Outliers skew mean, not median
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