ISEE Middle 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 Middle 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 $2, 5, 11, 23, _, 95$?

Answer: $47$. Each term follows the rule of multiplying the previous by $2$ and adding $1$, so apply to $23$.

Flashcard 2: What is the missing term in the sequence $1, 3, 6, 10, _, 21$?

Answer: $15$. The triangular number sequence follows $\frac{n(n+1)}{2}$ for $n=1$ to $5$, so the missing term is for $n=5$.

Flashcard 3: What is the missing term in the square-number sequence $1, 4, 9, _, 25$?

Answer: $16$. The sequence consists of squares of consecutive integers from $1^2$ to $5^2$, so the missing term is $4^2$.

Flashcard 4: What is the missing term in the triangular-number sequence $1, 3, 6, _, 15$?

Answer: $10$. The triangular number sequence is the sum of the first $n$ integers, so the missing term is for $n=4$.

Flashcard 5: What is the missing term in the arithmetic sequence $\frac{1}{2}, 1, \frac{3}{2}, _, \frac{5}{2}$?

Answer: $2$. The arithmetic sequence has a common difference of $\frac{1}{2}$, so the missing term is found by adding $\frac{1}{2}$ to $\frac{3}{2}$.

Flashcard 6: What is the missing term in the sequence $3^0, 3^1, _, 3^3, 3^4$?

Answer: $3^2$. The sequence is powers of $3$ with consecutive exponents from $0$ to $4$, so the missing term has exponent $2$.

Flashcard 7: What is the missing term in the arithmetic sequence $-3, 1, 5, _, 13$?

Answer: $9$. The arithmetic sequence has a common difference of $4$, so the missing term is found by adding $4$ to $5$.

Flashcard 8: What is the missing term in the arithmetic sequence $20, 15, 10, _, 0$?

Answer: $5$. The arithmetic sequence has a common difference of $-5$, so the missing term is found by subtracting $5$ from $10$.

Flashcard 9: What is the missing term in the sequence $1, 2, 4, 7, _, 16$?

Answer: $11$. The differences increase by $1$ each time ($+1, +2, +3, +4$), so add $4$ to $7$.

Flashcard 10: What is the missing term in the sequence $100, 50, 25, _, 6.25$?

Answer: $12.5$. The geometric sequence has a common ratio of $\frac{1}{2}$, so the missing term is found by multiplying $25$ by $\frac{1}{2}$.

Flashcard 11: What is the missing term in the cube-number sequence $1, 8, 27, _, 125$?

Answer: $64$. The sequence consists of cubes of consecutive integers from $1^3$ to $5^3$, so the missing term is $4^3$.

Flashcard 12: What is the missing term in the arithmetic sequence $4, 7, 10, _, 16$?

Answer: $13$. The arithmetic sequence has a common difference of $3$, so the missing term is found by adding $3$ to $10$.

Flashcard 13: What is the missing term in the geometric sequence $\frac{1}{4}, \frac{1}{2}, 1, _, 4$?

Answer: $2$. The geometric sequence has a common ratio of $2$, so the missing term is found by multiplying $1$ by $2$.

Flashcard 14: What is the missing term in the Fibonacci-type sequence $2, 3, 5, 8, _, 21$?

Answer: $13$. In this Fibonacci-type sequence, each term is the sum of the two preceding ones, so add $5$ and $8$.

Flashcard 15: What is the missing term in the sequence $\frac{1}{3}, \frac{1}{6}, \frac{1}{12}, _, \frac{1}{48}$?

Answer: $\frac{1}{24}$. The geometric sequence has a common ratio of $\frac{1}{2}$, so the missing term is found by multiplying $\frac{1}{12}$ by $\frac{1}{2}$.

Flashcard 16: What is the missing term in the sequence of powers $2^1, 2^2, 2^3, _, 2^5$?

Answer: $2^4$. The sequence is powers of $2$ with consecutive exponents from $1$ to $5$, so the missing term has exponent $4$.

Flashcard 17: What is the missing term in the sequence $0.2, 0.4, 0.8, _, 3.2$?

Answer: $1.6$. The geometric sequence has a common ratio of $2$, so the missing term is found by multiplying $0.8$ by $2$.

Flashcard 18: What is the missing term in the alternating sequence 2, 5, 4, 7, 6, _?

Answer: $9$. The sequence consists of two interleaved arithmetic sequences increasing by $2$, with odd positions starting at $2$ and even at $5$, so the sixth term follows the even sequence.

Flashcard 19: What is the missing term in the geometric sequence $3, 6, 12, _, 48$?

Answer: $24$. The geometric sequence has a common ratio of $2$, so the missing term is found by multiplying $12$ by $2$.

Flashcard 20: What is the missing term in the sequence 1, 4, 2, 8, 4, _?

Answer: $16$. The sequence alternates between multiplying by $4$ and dividing by $2$, so multiply $4$ by $4$.

Flashcard 21: What is the missing term in the geometric sequence $81, 27, 9, _, 1$?

Answer: $3$. The geometric sequence has a common ratio of $\frac{1}{3}$, so the missing term is found by multiplying $9$ by $\frac{1}{3}$.