Common Core: 1st Grade Math : Adding and Subtracting Within 20: CCSS.MATH.CONTENT.1.OA.C.6

Study concepts, example questions & explanations for Common Core: 1st Grade Math

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Example Questions

Example Question #142 : Common Core Math: Grade 1

\displaystyle \frac{\begin{array}[b]{r}14\\ -\ 7\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 6

\displaystyle 5

\displaystyle 9

\displaystyle 8

\displaystyle 7

Correct answer:

\displaystyle 7

Explanation:

To subtract we can count backwards. Start at \displaystyle 14 and count back \displaystyle 7.

\displaystyle 14, 13, 12, 11, 10, 9, 8, 7

\displaystyle \frac{\begin{array}[b]{r}14\\ -\ 7\end{array}}{ \ \ \ \space 7}

Example Question #591 : Operations

\displaystyle \frac{\begin{array}[b]{r}14\\ -\ 12\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 4

\displaystyle 5

\displaystyle 2

\displaystyle 6

\displaystyle 3

Correct answer:

\displaystyle 2

Explanation:

To subtract we can count backwards. Start at \displaystyle 14 and count back \displaystyle 12.

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

\displaystyle \frac{\begin{array}[b]{r}14\\ -\ 12\end{array}}{ \ \ \ \ \ \space 2}

Example Question #144 : Common Core Math: Grade 1

\displaystyle \frac{\begin{array}[b]{r}12\\ -\ 1\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 9

\displaystyle 10

\displaystyle 7

\displaystyle 11

\displaystyle 8

Correct answer:

\displaystyle 11

Explanation:

To subtract we can count backwards. Start at \displaystyle 12 and count back \displaystyle 1.

\displaystyle 12, 11

\displaystyle \frac{\begin{array}[b]{r}12\\ -\ 1\end{array}}{ \ \ \space 11}

Example Question #594 : How To Subtract

\displaystyle \frac{\begin{array}[b]{r}13\\ -\ 9\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 7

\displaystyle 5

\displaystyle 4

\displaystyle 3

\displaystyle 6

Correct answer:

\displaystyle 4

Explanation:

To subtract we can count backwards. Start at \displaystyle 13 and count back \displaystyle 9.

\displaystyle 13, 12, 11, 10, 9, 8, 7, 6, 5, 4

\displaystyle \frac{\begin{array}[b]{r}13\\ -\ 9\end{array}}{ \ \ \ \space 4}

Example Question #141 : Common Core Math: Grade 1

\displaystyle \frac{\begin{array}[b]{r}11\\ -\ 8\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 4

\displaystyle 3

\displaystyle 1

\displaystyle 2

\displaystyle 5

Correct answer:

\displaystyle 3

Explanation:

To subtract we can count backwards. Start at \displaystyle 11 and count back \displaystyle 8.

\displaystyle 11, 10, 9, 8, 7, 6, 5, 4, 3

\displaystyle \frac{\begin{array}[b]{r}11\\ -\ 8\end{array}}{ \ \ \ \space 3}

Example Question #21 : Adding And Subtracting Within 20: Ccss.Math.Content.1.Oa.C.6

\displaystyle \frac{\begin{array}[b]{r}10\\ -\ 4\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 7

\displaystyle 3

\displaystyle 4

\displaystyle 5

\displaystyle 6

Correct answer:

\displaystyle 6

Explanation:

To subtract we can count backwards. Start at \displaystyle 10 and count back \displaystyle 4.

\displaystyle 10, 9, 8, 7, 6

\displaystyle \frac{\begin{array}[b]{r}10\\ -\ 4\end{array}}{ \ \ \ \space 6}

Example Question #592 : Operations

\displaystyle \frac{\begin{array}[b]{r}9\\ -\ 2\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 9

\displaystyle 7

\displaystyle 5

\displaystyle 6

\displaystyle 8

Correct answer:

\displaystyle 7

Explanation:

To subtract we can count backwards. Start at \displaystyle 9 and count back \displaystyle 2.

\displaystyle 9,8,7

\displaystyle \frac{\begin{array}[b]{r}9\\ -\ 2\end{array}}{ \ \ \ \space 7}

Example Question #142 : Operations & Algebraic Thinking

\displaystyle \frac{\begin{array}[b]{r}8\\ -\ 4\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 6

\displaystyle 8

\displaystyle 7

\displaystyle 5

\displaystyle 4

Correct answer:

\displaystyle 4

Explanation:

To subtract we can count backwards. Start at \displaystyle 8 and count back \displaystyle 4.

\displaystyle 8,7,6,5,4

\displaystyle \frac{\begin{array}[b]{r}8\\ -\ 4\end{array}}{ \ \ \ \space 4}

Example Question #22 : Adding And Subtracting Within 20: Ccss.Math.Content.1.Oa.C.6

\displaystyle \frac{\begin{array}[b]{r}20\\ -\ 2\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 16

\displaystyle 18

\displaystyle 17

\displaystyle 15

\displaystyle 14

Correct answer:

\displaystyle 18

Explanation:

To subtract we can count backwards. Start at \displaystyle 20 and count back \displaystyle 2.

\displaystyle 20, 19, 18

\displaystyle \frac{\begin{array}[b]{r}20\\ -\ 2\end{array}}{ \ \ \space 18}

Example Question #51 : Adding And Subtracting Within 20

\displaystyle \frac{\begin{array}[b]{r}20\\ -\ 6\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 18

\displaystyle 15

\displaystyle 17

\displaystyle 14

\displaystyle 16

Correct answer:

\displaystyle 14

Explanation:

To subtract we can count backwards. Start at \displaystyle 20 and count back \displaystyle 6.

\displaystyle 20, 19, 18, 17, 16, 15, 14

\displaystyle \frac{\begin{array}[b]{r}20\\ -\ 6\end{array}}{ \ \ \space 14}

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