ISEE Lower Level Mathematics Achievement Flashcards: Missing Number In Sequences

What this deck covers

This deck focuses on Missing Number In Sequences, giving you a quick way to review the definitions, rules, and examples that matter most for ISEE Lower Level Mathematics Achievement.

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 arithmetic sequence $\frac{1}{2}, \frac{3}{2}, \square, \frac{7}{2}$?

Answer: $\frac{5}{2}$. The common difference is $1$, determined from $\frac{3}{2} - \frac{1}{2}$, and added to $\frac{3}{2}$ to find the missing term.

Flashcard 2: What is the missing term in the arithmetic sequence $\frac{5}{4}, \frac{3}{4}, \square, -\frac{1}{4}$?

Answer: $\frac{1}{4}$. The common difference is $-\frac{1}{2}$, determined from $\frac{3}{4} - \frac{5}{4}$, and added to $\frac{3}{4}$ to find the missing term.

Flashcard 3: What is the missing term in the arithmetic sequence $1, 4, 7, \square$?

Answer: $10$. The common difference is $3$, determined from $4 - 1$, and added to $7$ to find the missing term.

Flashcard 4: What is the missing term in the arithmetic sequence $-3, \square, 5, 9$?

Answer: $1$. The common difference is $4$, determined from $9 - 5$, and subtracted from $5$ to find the missing term.

Flashcard 5: What is the missing term in the arithmetic sequence $8, 3, \square, -7$?

Answer: $-2$. The common difference is $-5$, determined from $3 - 8$, and added to $3$ to find the missing term.

Flashcard 6: What is the missing term in the arithmetic sequence $30, 24, \square, 12$?

Answer: $18$. The common difference is $-6$, determined from $24 - 30$, and added to $24$ to find the missing term.

Flashcard 7: What is the missing term in the arithmetic sequence $-10, -6, -2, \square$?

Answer: $2$. The common difference is $4$, determined from $-6 - (-10)$, and added to $-2$ to find the missing term.

Flashcard 8: What is the missing term in the arithmetic sequence $3, 8, \square, 18$?

Answer: $13$. The common difference is $5$, determined from $8 - 3$, and added to $8$ to find the missing term.

Flashcard 9: What is the missing term in the arithmetic sequence $9, 6, 3, \square$?

Answer: $0$. The common difference is $-3$, determined from $6 - 9$, and added to $3$ to find the missing term.

Flashcard 10: What is the missing term in the arithmetic sequence $\square, -1, 2, 5$?

Answer: $-4$. The common difference is $3$, determined from $2 - (-1)$, and subtracted from $-1$ to find the missing term.

Flashcard 11: What is the missing term in the arithmetic sequence $12, 9, 6, \square$?

Answer: $3$. The common difference is $-3$, determined from $9 - 12$, and added to $6$ to find the missing term.

Flashcard 12: What is the common difference $d$ in the arithmetic sequence $7, 11, 15, \dots$?

Answer: $d=4$. The common difference $d$ is found by subtracting the first term from the second, yielding $11 - 7 = 4$, consistent with $15 - 11 = 4$.

Flashcard 13: What is the missing term in the arithmetic sequence $\square, 14, 18, 22$?

Answer: $10$. The common difference is $4$, determined from $18 - 14$, and subtracted from $14$ to find the missing term.

Flashcard 14: What is the missing term in the arithmetic sequence $\frac{2}{3}, \square, \frac{8}{3}, \frac{11}{3}$?

Answer: $\frac{5}{3}$. The common difference is $1$, determined from $\frac{11}{3} - \frac{8}{3}$, and subtracted from $\frac{8}{3}$ to find the missing term.

Flashcard 15: What is the missing term in the arithmetic sequence $100, 90, \square, 70$?

Answer: $80$. The common difference is $-10$, determined from $90 - 100$, and added to $90$ to find the missing term.

Flashcard 16: What is the missing term in the arithmetic sequence $4, \square, 10, 13$?

Answer: $7$. The common difference is $3$, determined from $13 - 10$, and subtracted from $10$ to find the missing term.

Flashcard 17: What is the missing term in the arithmetic sequence $2.5, 3.0, \square, 4.0$?

Answer: $3.5$. The common difference is $0.5$, determined from $3.0 - 2.5$, and added to $3.0$ to find the missing term.

Flashcard 18: What is the missing term in the arithmetic sequence $-2, 1, \square, 7$?

Answer: $4$. The common difference is $3$, determined from $1 - (-2)$, and added to $1$ to find the missing term.

Flashcard 19: What is the missing term in the arithmetic sequence $6, \square, 16, 21$?

Answer: $11$. The common difference is $5$, determined from $21 - 16$, and subtracted from $16$ to find the missing term.

Flashcard 20: What is the missing term in the arithmetic sequence $20, \square, 10, 5$?

Answer: $15$. The common difference is $-5$, determined from $10 - 15$ or $5 - 10$, and added to $20$ to find the missing term.

Flashcard 21: What is the missing term in the arithmetic sequence $-1.2, -0.7, \square, 0.3$?

Answer: $-0.2$. The common difference is $0.5$, determined from $-0.7 - (-1.2)$, and added to $-0.7$ to find the missing term.

Flashcard 22: What is the missing term in the arithmetic sequence $5, 2, \square, -4$?

Answer: $-1$. The common difference is $-3$, determined from $2 - 5$, and added to $2$ to find the missing term.

Flashcard 23: What is the missing term in the arithmetic sequence $2, 2.8, \square, 4.4$?

Answer: $3.6$. The common difference is $0.8$, determined from $2.8 - 2$, and added to $2.8$ to find the missing term.

Flashcard 24: What is the missing term in the arithmetic sequence $15, \square, 5, 0$?

Answer: $10$. The common difference is $-5$, determined from $5 - 10$ or $0 - 5$, and added to $15$ to find the missing term.