2020
2020 AMC12 Paper & Solutions Pick Paper A
25 complete solutions, number theory weight increased with prime factorization and divisibility. Geometry focuses on area.

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25 Questions
75 Minutes
Max Score 150
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Exam Overview
Exam Overview
>, Area.
Difficulty
- EasyQ1-10
- MediumQ11-20
- HardQ21-25
Topics
- Algebra30%
- Geometry30%
- Number Theory25%
- Combinatorics15%
Awards
AIME Qualification
AIME Qualification (Top 2.5%)
93+
Honor Roll
Honor Roll (Top 5%)
79+
Achievement Roll
Grade 10 and below
62+
Sample Problems
2020 AMC12 Sample Problems (12 questions)
Sample reference problems by difficulty — click an option to check your answer
Q1EasyPolynomial
If f(x) = 2x² - 3x + 3, find f(2).
Steps
1f(2) = 2×2² - 3×2 + 3
2= 2×4 - 6 + 3 = 5
Answer: ASubstitute, then exponentiate, multiply/divide, add/subtract
Q3EasyArithmetic Seq
Arithmetic sequence: a₁=3, d=2, find the 12-th term.
Steps
1aₙ = a₁ + (n-1)d
2a_12 = 3 + 11×2 = 25
Answer: BGeneral term: aₙ=a₁+(n-1)d
Q5EasyExponent
If 4ˣ = 64, find x.
Steps
164 = 4^3
2so x = 3
Answer: CConvert to same base, compare exponents
Q7EasyVieta's
Sum of roots of x² - 5x + 4 = 0?
Steps
1Vieta's:sum of roots = -(-5)/1 = 5
2product of roots = 4
Answer: DFor x²-px+q=0, sum of roots = p
Q10MediumDivisibility
How many integers from 1 to 30 are divisible by 5?
Steps
1⌊30 / 5⌋ = 6
Answer: ECount divisible by k: ⌊n/k⌋
Q12MediumDiagonals
How many diagonals does a regular 9-gon have?
Steps
1diagonals = n(n-3)/2
2= 9×6/2 = 27
Answer: An-gon diagonals: n(n-3)/2
Q15MediumCombination
Compute C(6, 3).
Steps
1C(n,3) = n(n-1)(n-2)/6
2= 6×5×4/6 = 20
Answer: BCombination: C(n,k)=n!/(k!(n-k)!)
Q17MediumPythagorean
Right triangle legs 3 and 4, find the hypotenuse.
Steps
1c² = 3² + 4² = 9 + 16 = 25
2c = √25 = 5
Answer: CPythagorean theorem a²+b²=c²
Q20HardModular Arith
Find the remainder of 3^6 divided by 5.
Steps
1compute 3^6 mod 5
2simplify step by step (modular arithmetic)
3=4
Answer: DModular arithmetic simplifies large exponents
Q22HardCompleting Sq
Find the minimum of f(x) = x² - 4x + 9.
Steps
1complete the square:f(x) = (x - 2)² + 5
2when x = 2 , min at 5
Answer: ECompleting the square for quadratic extrema
Q24HardInclusion-Excl
6 distinct balls into 3 distinct boxes, each ≥1 ball, how many ways?
Steps
1total 3^6 = 729
2subtract empty boxes: -C(3,1)×2^6 = -192
3add back 2 empty boxes: +C(3,2)×1 = +3
4total 729 - 192 + 3 = 540
Answer: AInclusion-exclusion handles 'at least'
Q25HardLaw of Cosines
In △ABC, a=7, b=8, cos C=1/2, find c².
Steps
1Law of cosines c² = a² + b² - 2ab·cos C
2= 49 + 64 - 56 = 57
Answer: BLaw of cosines is key for solving triangles
Q1EasyPolynomial
If f(x) = 2x² - 5x + 3, find f(2).
Steps
1f(2) = 2×2² - 5×2 + 3
2= 2×4 - 10 + 3 = 1
Answer: ASubstitute, then exponentiate, multiply/divide, add/subtract
Q3EasyArithmetic Seq
Arithmetic sequence: a₁=5, d=2, find the 12-th term.
Steps
1aₙ = a₁ + (n-1)d
2a_12 = 5 + 11×2 = 27
Answer: BGeneral term: aₙ=a₁+(n-1)d
Q5EasyExponent
If 4ˣ = 64, find x.
Steps
164 = 4^3
2so x = 3
Answer: CConvert to same base, compare exponents
Q7EasyVieta's
Sum of roots of x² - 7x + 4 = 0?
Steps
1Vieta's:sum of roots = -(-7)/1 = 7
2product of roots = 4
Answer: DFor x²-px+q=0, sum of roots = p
Q10MediumDivisibility
How many integers from 1 to 32 are divisible by 5?
Steps
1⌊32 / 5⌋ = 6
Answer: ECount divisible by k: ⌊n/k⌋
Q12MediumDiagonals
How many diagonals does a regular 11-gon have?
Steps
1diagonals = n(n-3)/2
2= 11×8/2 = 44
Answer: An-gon diagonals: n(n-3)/2
Q15MediumCombination
Compute C(8, 3).
Steps
1C(n,3) = n(n-1)(n-2)/6
2= 8×7×6/6 = 56
Answer: BCombination: C(n,k)=n!/(k!(n-k)!)
Q17MediumPythagorean
Right triangle legs 6 and 8, find the hypotenuse.
Steps
1c² = 6² + 8² = 36 + 64 = 100
2c = √100 = 10
Answer: CPythagorean theorem a²+b²=c²
Q20HardModular Arith
Find the remainder of 3^6 divided by 5.
Steps
1compute 3^6 mod 5
2simplify step by step (modular arithmetic)
3=4
Answer: DModular arithmetic simplifies large exponents
Q22HardCompleting Sq
Find the minimum of f(x) = x² - 4x + 11.
Steps
1complete the square:f(x) = (x - 2)² + 7
2when x = 2 , min at 7
Answer: ECompleting the square for quadratic extrema
Q24HardInclusion-Excl
6 distinct balls into 3 distinct boxes, each ≥1 ball, how many ways?
Steps
1total 3^6 = 729
2subtract empty boxes: -C(3,1)×2^6 = -192
3add back 2 empty boxes: +C(3,2)×1 = +3
4total 729 - 192 + 3 = 540
Answer: AInclusion-exclusion handles 'at least'
Q25HardLaw of Cosines
In △ABC, a=9, b=8, cos C=1/2, find c².
Steps
1Law of cosines c² = a² + b² - 2ab·cos C
2= 81 + 64 - 72 = 73
Answer: BLaw of cosines is key for solving triangles
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