Practice Test GeeksAMC 8 - American Mathematics Competition 8 Practice Test
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Number Theory & Divisibility Flashcards

6 cards from real AMC 8 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 Number Theory & Divisibility flashcards as text

  1. What is the greatest common factor (GCF) of 48 and 36?

    Answer: 12

    The GCF of 48 and 36 is 12, since 12 divides both and no larger number does.

  2. Which of the following is a prime number?

    Answer: 61

    61 is prime because it has no factors other than 1 and itself.

  3. What is the least common multiple (LCM) of 6 and 8?

    Answer: 24

    The LCM of 6 and 8 is 24, the smallest positive number divisible by both.

  4. How many positive factors does 36 have?

    Answer: 9

    36 = 2² × 3² has (2+1)(2+1) = 9 factors: 1, 2, 3, 4, 6, 9, 12, 18, 36.

  5. What is the sum of all positive factors of 12?

    Answer: 28

    The factors of 12 are 1, 2, 3, 4, 6, 12, and 1+2+3+4+6+12 = 28.

  6. If a number leaves a remainder of 3 when divided by 7, what remainder does twice that number leave when divided by 7?

    Answer: 6

    If n ≡ 3 (mod 7), then 2n ≡ 6 (mod 7).