Common Core: 2nd Grade Math : Operations & Algebraic Thinking

Study concepts, example questions & explanations for Common Core: 2nd Grade Math

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Example Questions

Example Question #1651 : Common Core Math: Grade 2

\(\displaystyle \frac{\begin{array}[b]{r}20\\ -\ 1\end{array}}{ \ \ \ \space?}\)

Possible Answers:

\(\displaystyle 19\)

\(\displaystyle 17\)

\(\displaystyle 18\)

\(\displaystyle 16\)

\(\displaystyle 15\)

Correct answer:

\(\displaystyle 19\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 20\) and count back \(\displaystyle 1.\)

\(\displaystyle 20,19\)

\(\displaystyle \frac{\begin{array}[b]{r}20\\ -\ 1\end{array}}{ \ \ \space19}\)

Example Question #1651 : Common Core Math: Grade 2

\(\displaystyle \frac{\begin{array}[b]{r}19\\ -\ 2\end{array}}{ \ \ \ \space?}\)

Possible Answers:

\(\displaystyle 18\)

\(\displaystyle 17\)

\(\displaystyle 14\)

\(\displaystyle 16\)

\(\displaystyle 15\)

Correct answer:

\(\displaystyle 17\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 19\) and count back \(\displaystyle 2.\)

\(\displaystyle 19,18,17\)

\(\displaystyle \frac{\begin{array}[b]{r}19\\ -\ 2\end{array}}{ \ \ \space17}\)

Example Question #1 : Operations & Algebraic Thinking

Solve the following: 

\(\displaystyle \frac{\begin{array}[b]{r}16\\ -\ 14\end{array}}{ \ \ \ \space}\)

Possible Answers:

\(\displaystyle 4\)

\(\displaystyle 3\)

\(\displaystyle 2\)

\(\displaystyle 6\)

\(\displaystyle 5\)

Correct answer:

\(\displaystyle 2\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 16\) and count back \(\displaystyle 14.\)

\(\displaystyle 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2\)

\(\displaystyle \frac{\begin{array}[b]{r}16\\ -\ 14\end{array}}{ \ \ \ \ \ \space2}\)

Example Question #1652 : Common Core Math: Grade 2

\(\displaystyle \frac{\begin{array}[b]{r}13\\ -\ 6\end{array}}{ \ \ \ \space?}\)

Possible Answers:

\(\displaystyle 5\)

\(\displaystyle 8\)

\(\displaystyle 6\)

\(\displaystyle 9\)

\(\displaystyle 7\)

Correct answer:

\(\displaystyle 7\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 13\) and count back \(\displaystyle 6\).

\(\displaystyle 13, 12, 11, 10, 9, 8, 7\)

\(\displaystyle \frac{\begin{array}[b]{r}13\\ -\ 6\end{array}}{ \ \ \ \space7}\)

Example Question #1 : Operations & Algebraic Thinking

\(\displaystyle \frac{\begin{array}[b]{r}9\\ -\ 3\end{array}}{ \ \ \ \space?}\)

Possible Answers:

\(\displaystyle 2\)

\(\displaystyle 8\)

\(\displaystyle 6\)

\(\displaystyle 5\)

\(\displaystyle 7\)

Correct answer:

\(\displaystyle 6\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 9\) and count back \(\displaystyle 3\).

\(\displaystyle 9, 8, 7, 6\)

\(\displaystyle \frac{\begin{array}[b]{r}9\\ -\ 3\end{array}}{ \ \ \ \space6}\)

Example Question #1 : Operations & Algebraic Thinking

\(\displaystyle \frac{\begin{array}[b]{r}7\\ -\ 7\end{array}}{ \ \ \ \space?}\)

Possible Answers:

\(\displaystyle 2\)

\(\displaystyle 0\)

\(\displaystyle 7\)

\(\displaystyle 1\)

\(\displaystyle 3\)

Correct answer:

\(\displaystyle 0\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 7\) and count back \(\displaystyle 7\).

\(\displaystyle 7, 6, 5, 4, 3, 2, 1, 0\)

\(\displaystyle \frac{\begin{array}[b]{r}7\\ -\ 7\end{array}}{ \ \ \ \space0}\)

Example Question #2 : Operations & Algebraic Thinking

\(\displaystyle \frac{\begin{array}[b]{r}6\\ -\ 5\end{array}}{ \ \ \ \space?}\)

Possible Answers:

\(\displaystyle 0\)

\(\displaystyle 2\)

\(\displaystyle 6\)

\(\displaystyle 1\)

\(\displaystyle 5\)

Correct answer:

\(\displaystyle 1\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 6\) and count back \(\displaystyle 5\).

\(\displaystyle 6, 5, 4, 3, 2, 1\)

\(\displaystyle \frac{\begin{array}[b]{r}6\\ -\ 5\end{array}}{ \ \ \ \space1}\)

Example Question #1 : Mentally Add And Subtract Within 20: Ccss.Math.Content.2.Oa.B.2

\(\displaystyle \frac{\begin{array}[b]{r}5\\ -\ 3\end{array}}{ \ \ \ \space?}\)

Possible Answers:

\(\displaystyle 0\)

\(\displaystyle 5\)

\(\displaystyle 4\)

\(\displaystyle 1\)

\(\displaystyle 2\)

Correct answer:

\(\displaystyle 2\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 5\) and count back \(\displaystyle 3\).

\(\displaystyle 5, 4, 3, 2\)

\(\displaystyle \frac{\begin{array}[b]{r}5\\ -\ 3\end{array}}{ \ \ \ \space2}\)

Example Question #1 : Operations & Algebraic Thinking

\(\displaystyle \frac{\begin{array}[b]{r}4\\ -\ 1\end{array}}{ \ \ \ \space?}\)

Possible Answers:

\(\displaystyle 0\)

\(\displaystyle 3\)

\(\displaystyle 4\)

\(\displaystyle 5\)

\(\displaystyle 2\)

Correct answer:

\(\displaystyle 3\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 4\) and count back \(\displaystyle 1.\)

\(\displaystyle 4, 3\)

\(\displaystyle \frac{\begin{array}[b]{r}4\\ -\ 1\end{array}}{ \ \ \ \space3}\)

Example Question #2 : Mentally Add And Subtract Within 20: Ccss.Math.Content.2.Oa.B.2

\(\displaystyle \frac{\begin{array}[b]{r}7\\ -\ 2\end{array}}{ \ \ \ \space?}\)

Possible Answers:

\(\displaystyle 6\)

\(\displaystyle 3\)

\(\displaystyle 4\)

\(\displaystyle 5\)

\(\displaystyle 2\)

Correct answer:

\(\displaystyle 5\)

Explanation:

To subtract we can count backwards. Start at \(\displaystyle 7\) and count back \(\displaystyle 2\).

\(\displaystyle 7, 6, 5\)

\(\displaystyle \frac{\begin{array}[b]{r}7\\ -\ 2\end{array}}{ \ \ \ \space5}\)

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