ISEE Lower Level Quantitative Reasoning Flashcards: Missing Sequence Terms

What this deck covers

This deck focuses on Missing Sequence Terms, giving you a quick way to review the definitions, rules, and examples that matter most for ISEE Lower Level Quantitative Reasoning.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is the missing term in the sequence $100, 50, 25, _, 6.25$?

Answer: $12.5$. The sequence is geometric with a common ratio of $\frac{1}{2}$, so the term after $25$ is $25 \times \frac{1}{2} = 12.5$.

Flashcard 2: What is the missing term in the arithmetic sequence $3, _, 13, 18, 23$?

Answer: $8$. The sequence is arithmetic with a common difference of $5$, so the term after $3$ is $3 + 5 = 8$.

Flashcard 3: What is the missing term in the sequence $2, 4, 7, 11, _, 22$ if the differences are $+2, +3, +4, \dots$?

Answer: $16$. The differences increase by $1$ each time starting from $+2$, so the term after $11$ is $11 + 5 = 16$.

Flashcard 4: What is the missing term in the sequence $-2, 1, 4, _, 10$?

Answer: $7$. The sequence is arithmetic with a common difference of $3$, so the term after $4$ is $4 + 3 = 7$.

Flashcard 5: What is the missing term in the arithmetic sequence $12, 9, 6, _, 0$?

Answer: $3$. The sequence is arithmetic with a common difference of $-3$, so the term after $6$ is $6 - 3 = 3$.

Flashcard 6: What is the missing term in the sequence $5, 6, 8, 11, _, 20$ if the differences are $+1, +2, +3, \dots$?

Answer: $15$. The differences increase by $1$ each time starting from $+1$, so the term after $11$ is $11 + 4 = 15$.

Flashcard 7: What is the missing term in the Fibonacci-type sequence $1, 1, 2, 3, _, 8$?

Answer: $5$. The sequence follows the Fibonacci rule where each term is the sum of the two preceding ones, so the term after $3$ is $2 + 3 = 5$.

Flashcard 8: What is the missing term in the sequence $1, 3, 6, 10, _, 21$ (triangular numbers)?

Answer: $15$. The sequence consists of triangular numbers where each term adds the next integer, so the term after $10$ is $10 + 5 = 15$.

Flashcard 9: What is the missing term in 1, 2, 4, 7, 11, _ if the differences increase by $1$ each time?

Answer: $16$. The differences increase by $1$ each time starting from $+1$, so the term after $11$ is $11 + 5 = 16$.

Flashcard 10: What is the missing term in the sequence $9, 6, 8, 5, 7, _, 6$ (alternating $-3, +2$)?

Answer: $4$. The sequence alternates between subtracting $3$ and adding $2$, so the term after $7$ is $7 - 3 = 4$.

Flashcard 11: What is the missing term in the sequence $4, 9, 14, _, 24$?

Answer: $19$. The sequence is arithmetic with a common difference of $5$, so the term after $14$ is $14 + 5 = 19$.

Flashcard 12: What is the missing term in the geometric sequence $\frac{1}{2}, 1, 2, _, 8$?

Answer: $4$. The sequence is geometric with a common ratio of $2$, so the term after $2$ is $2 \times 2 = 4$.

Flashcard 13: What is the missing term in the Fibonacci-type sequence $2, 3, 5, 8, _, 21$?

Answer: $13$. The sequence follows the Fibonacci rule where each term is the sum of the two preceding ones, so the term after $8$ is $5 + 8 = 13$.

Flashcard 14: What is the missing term in the geometric sequence $5, _, 45, 135$?

Answer: $15$. The sequence is geometric with a common ratio of $3$, so the term after $5$ is $5 \times 3 = 15$.

Flashcard 15: What is the missing term in the arithmetic sequence $-4, -1, 2, _, 8$?

Answer: $5$. The sequence is arithmetic with a common difference of $3$, so the term after $2$ is $2 + 3 = 5$.

Flashcard 16: What is the missing term in the sequence of perfect cubes $1, 8, _, 64, 125$?

Answer: $27$. The sequence consists of perfect cubes, so the term after $8$ is $3^3 = 27$.

Flashcard 17: What is the missing term in the sequence 3, 6, 12, 24, _?

Answer: $48$. The sequence is geometric with a common ratio of $2$, so the term after $24$ is $24 \times 2 = 48$.

Flashcard 18: What is the missing term in the sequence $2, 5, 10, 17, _, 37$ if the rule is $+3, +5, +7, \dots$?

Answer: $26$. The differences increase by $2$ each time starting from $+3$, so the term after $17$ is $17 + 9 = 26$.

Flashcard 19: What is the missing term in the geometric sequence $2, 6, 18, _, 162$?

Answer: $54$. The sequence is geometric with a common ratio of $3$, so the term after $18$ is $18 \times 3 = 54$.

Flashcard 20: What is the missing term in the geometric sequence $81, 27, 9, _, 1$?

Answer: $3$. The sequence is geometric with a common ratio of $\frac{1}{3}$, so the term after $9$ is $9 \times \frac{1}{3} = 3$.

Flashcard 21: What is the missing term in the sequence of perfect squares $1, 4, _, 16, 25$?

Answer: $9$. The sequence consists of perfect squares, so the term after $4$ is $3^2 = 9$.

Flashcard 22: What is the missing term in the arithmetic sequence $7, 11, 15, _, 23$?

Answer: $19$. The sequence is arithmetic with a common difference of $4$, so the term after $15$ is $15 + 4 = 19$.