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ASVAB Ready
ASVAB Cheat Sheet

ASVAB cheat sheets

The formulas, rules and facts worth memorising for every ASVAB subtest, in one place. Pair each with the full study guides and free practice.

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Arithmetic Reasoning (AR)

Full guide
Core formulas
  • Distance = rate × time (rate = dist ÷ time, time = dist ÷ rate)
  • Part = percent × whole; percent = part ÷ whole
  • Percent change = (new − old) ÷ old
  • Discount / markup: multiply by (1 − r) or (1 + r)
  • Simple interest: I = P × r × t
  • Average = sum ÷ count; unit rate = total ÷ number of units
Ratios & work
  • Split in ratio a:b:c → divide the total by (a + b + c) to get one 'part'
  • Combined work: rates ADD (1/a + 1/b), or total worker-days = workers × days
  • Average speed = total distance ÷ total time (NOT the average of the two speeds)
Common traps
  • 'half an hour' = 30 minutes — multiply, don't ÷ 2
  • 'one in every N' → the rest = total − (total ÷ N)
  • Compound depreciation: multiply by (1 − r) each year; don't just take r × years

Mathematics Knowledge (MK)

Full guide
Order & exponents
  • PEMDAS: brackets, exponents, × & ÷, then + & −
  • Same base: multiply → ADD exponents; divide → SUBTRACT; power of a power → MULTIPLY
  • x^0 = 1; x^(−n) = 1 / x^n; x^(1/2) = √x
Algebra
  • Difference of squares: a² − b² = (a − b)(a + b)
  • Slope = (y₂ − y₁) ÷ (x₂ − x₁)
  • Isolate the variable with inverse operations on both sides
Geometry
  • Rectangle area = l × w; triangle area = ½ × base × height
  • Circle: area = πr², circumference = 2πr
  • Box volume = l × w × h; cylinder = πr²h
  • Pythagoras: a² + b² = c²
  • Angles: triangle = 180°, straight line = 180°, full circle = 360°
Numbers
  • Prime = only factors 1 and itself; GCF = largest shared factor; LCM = smallest shared multiple

Word Knowledge (WK)

Full guide
Roots
  • bene = good · mal = bad · spec = look · dict = say · port = carry
  • scrib/scrip = write · aud = hear · vis/vid = see · duc = lead
Prefixes & suffixes
  • un-/in-/im- = not · re- = again · pre- = before · sub- = under · anti- = against · mis- = wrong
  • -able = can be · -ous = full of · -tion = act of · -ful = full of · -less = without
Strategy
  • If the word is in a sentence, use the context; predict the meaning, then match
  • Pick the CLOSEST synonym; watch for an antonym hidden among the options

Paragraph Comprehension (PC)

Full guide
Approach
  • Read the question first, then read the passage for it
  • Main idea = what the WHOLE passage supports (not one detail)
  • Inference = must be true from the text, not merely plausible
  • Vocabulary-in-context = substitute each option back into the sentence
  • Answer only from the passage — never outside knowledge

General Science (GS)

Full guide
Life science
  • Mitochondria = energy (ATP) · nucleus = DNA · chloroplast = photosynthesis · ribosome = proteins
  • Photosynthesis: CO₂ + water + light → sugar + O₂; respiration is the reverse
  • Humans: 206 bones, 46 chromosomes (23 pairs), heart has 4 chambers
Earth & space
  • Earth layers: crust, mantle, core; rocks: igneous, sedimentary, metamorphic
  • Planet order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Physical science
  • Atom: protons (+), neutrons (0), electrons (−); atomic number = number of protons
  • pH < 7 acidic, 7 neutral, > 7 basic
  • Water freezes 0°C/32°F, boils 100°C/212°F; F = 1.8 × C + 32
  • Work = force × distance; speed of light ≈ 3 × 10^8 m/s

Electronics Information (EI)

Full guide
Laws
  • Ohm's law: V = I × R (I = V ÷ R, R = V ÷ I)
  • Power: P = V × I = I²R = V²/R
Circuits
  • Series: resistances ADD; current is the same everywhere
  • Parallel: voltage is the same across branches; two resistors R = product ÷ sum; total R drops
Know these
  • Units: volt (V), amp (A), ohm (Ω), watt (W), farad (F), hertz (Hz)
  • Resistor limits current · capacitor stores charge · diode = one-way · transistor = switch/amplify · transformer changes AC voltage · fuse protects
  • Conductor (copper) vs insulator (rubber/glass) vs semiconductor (silicon)
  • AC = alternating current · DC = direct current · an ohmmeter measures resistance

Auto Information (AI)

Full guide
Engine
  • Four-stroke cycle in order: Intake → Compression → Power → Exhaust
  • Gasoline engine ignites with a SPARK PLUG; diesel ignites by COMPRESSION (no spark plug)
Systems
  • Cooling: radiator, thermostat, water pump, coolant/antifreeze
  • Charging: battery, ALTERNATOR (charges the battery), starter
  • Drivetrain: clutch, transmission (changes gear ratios), differential
  • Emissions: catalytic converter · Lubrication: oil & oil pump
  • Shock absorbers connect the axle to the chassis

Shop Information (SI)

Full guide
Measuring & layout
  • Spirit LEVEL = horizontal · PLUMB BOB = vertical · SQUARE = right angles
  • FEELER GAUGE measures small gaps (e.g. a spark-plug gap)
Cutting & fastening
  • RIPSAW cuts WITH the grain · CROSSCUT saw cuts ACROSS · HACKSAW cuts metal
  • A BOLT uses a nut; a SCREW threads into the material
  • TAP cuts internal threads; DIE cuts external threads
  • 'Righty-tighty, lefty-loosey'; a sanding block prevents high spots and ridges

Mechanical Comprehension (MC)

Full guide
Machines & advantage
  • Mechanical advantage = output ÷ input force = effort arm ÷ load arm (lever)
  • Balance a lever/seesaw: effort × its arm = load × its arm
  • Fixed pulley: MA = 1 (direction only); each supporting rope in a movable system adds to the MA
  • Gears: speed ∝ 1 ÷ number of teeth (bigger gear = slower, more torque); meshed gears turn opposite ways
Forces & fluids
  • Work = force × distance (a machine trades force for distance, not total work)
  • Pressure = force ÷ area; hydraulics/Pascal: a bigger piston gives more output force
  • Buoyancy: upward force = weight of displaced fluid (water ≈ 62.4 lb/ft³)
  • Center of gravity: extending a load shifts it; a wider, lower base is more stable