Common Core: 1st Grade Math : Adding and Subtracting Within 20

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

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Example Questions

Example Question #171 : Adding And Subtracting Within 20

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

Possible Answers:

\displaystyle 2

\displaystyle 4

\displaystyle 0

\displaystyle 3

\displaystyle 1

Correct answer:

\displaystyle 0

Explanation:

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

\displaystyle 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0

\displaystyle \frac{\begin{array}[b]{r}14\\ -\ 14\end{array}}{ \ \ \ \space 0}

Example Question #172 : Adding And Subtracting Within 20

\displaystyle \frac{\begin{array}[b]{r}19\\ -\ 10\end{array}}{ \ \ \ \space ?}

Possible Answers:

\displaystyle 6

\displaystyle 9

\displaystyle 10

\displaystyle 8

\displaystyle 7

Correct answer:

\displaystyle 9

Explanation:

To subtract we can count backwards. Start at \displaystyle 19 and count back \displaystyle 10.

\displaystyle 19, 18, 17, 16, 15, 14, 13, 12, 11, 10,9

\displaystyle \frac{\begin{array}[b]{r}19\\ -\ 10\end{array}}{ \ \ \ \ \space 9}

Example Question #173 : Adding And Subtracting Within 20

\displaystyle \frac{\begin{array}[b]{r}19\\ -\ 14\end{array}}{ \ \ \ \ \space ?}

Possible Answers:

\displaystyle 6

\displaystyle 7

\displaystyle 3

\displaystyle 5

\displaystyle 4

Correct answer:

\displaystyle 5

Explanation:

To subtract we can count backwards. Start at \displaystyle 19 and count back \displaystyle 14.

\displaystyle 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5

\displaystyle \frac{\begin{array}[b]{r}19\\ -\ 14\end{array}}{ \ \ \ \ \space 5}

Example Question #271 : Common Core Math: Grade 1

\displaystyle \frac{\begin{array}[b]{r}15\\ -\ 14\end{array}}{ \ \ \ \ \space ?}

Possible Answers:

\displaystyle 1

\displaystyle 2

\displaystyle 3

\displaystyle 4

\displaystyle 5

Correct answer:

\displaystyle 1

Explanation:

To subtract we can count backwards. Start at \displaystyle 15 and count back \displaystyle 14.

\displaystyle 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1

\displaystyle \frac{\begin{array}[b]{r}15\\ -\ 14\end{array}}{ \ \ \ \ \ \space 1}

Example Question #272 : Common Core Math: Grade 1

\displaystyle \frac{\begin{array}[b]{r}13\\ -\ 1\end{array}}{ \ \ \ \ \space ?}

Possible Answers:

\displaystyle 11

\displaystyle 10

\displaystyle 12

\displaystyle 8

\displaystyle 9

Correct answer:

\displaystyle 12

Explanation:

To subtract we can count backwards. Start at \displaystyle 13 and count back \displaystyle 1.

\displaystyle 13,12

\displaystyle \frac{\begin{array}[b]{r}13\\ -\ 1\end{array}}{ \ \ \space 12}

Example Question #273 : Common Core Math: Grade 1

\displaystyle \frac{\begin{array}[b]{r}12\\ -\ 8\end{array}}{ \ \ \ \ \space ?}

Possible Answers:

\displaystyle 7

\displaystyle 6

\displaystyle 3

\displaystyle 4

\displaystyle 5

Correct answer:

\displaystyle 4

Explanation:

To subtract we can count backwards. Start at \displaystyle 12 and count back \displaystyle 8.

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

\displaystyle \frac{\begin{array}[b]{r}12\\ -\ 8\end{array}}{ \ \ \ \ \space 4}

Example Question #274 : Common Core Math: Grade 1

\displaystyle \frac{\begin{array}[b]{r}12\\ -\ 10\end{array}}{ \ \ \ \ \space ?}

Possible Answers:

\displaystyle 4

\displaystyle 1

\displaystyle 0

\displaystyle 2

\displaystyle 3

Correct answer:

\displaystyle 2

Explanation:

To subtract we can count backwards. Start at \displaystyle 12 and count back \displaystyle 10.

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

\displaystyle \frac{\begin{array}[b]{r}12\\ -\ 10\end{array}}{ \ \ \ \ \ \space 2}

Example Question #275 : Common Core Math: Grade 1

\displaystyle \frac{\begin{array}[b]{r}11\\ -\ 10\end{array}}{ \ \ \ \ \space ?}

Possible Answers:

\displaystyle 4

\displaystyle 1

\displaystyle 5

\displaystyle 3

\displaystyle 2

Correct answer:

\displaystyle 1

Explanation:

To subtract we can count backwards. Start at \displaystyle 11 and count back \displaystyle 10.

\displaystyle 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1

\displaystyle \frac{\begin{array}[b]{r}11\\ -\ 10\end{array}}{ \ \ \ \ \ \space 1}

Example Question #276 : Common Core Math: Grade 1

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

Possible Answers:

\displaystyle 1

\displaystyle 3

\displaystyle 2

\displaystyle 0

\displaystyle 4

Correct answer:

\displaystyle 0

Explanation:

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

\displaystyle 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0

\displaystyle \frac{\begin{array}[b]{r}11\\ -\ 11\end{array}}{ \ \ \ \ \space 0}

Example Question #277 : Common Core Math: Grade 1

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

Possible Answers:

\displaystyle 3

\displaystyle 4

\displaystyle 2

\displaystyle 0

\displaystyle 1

Correct answer:

\displaystyle 0

Explanation:

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

\displaystyle 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0

\displaystyle \frac{\begin{array}[b]{r}10\\ -\ 10\end{array}}{ \ \ \ \ \space 0}

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