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 #11 : Adding And Subtracting Within 20

Fill in the blank: \(\displaystyle 5\)\(\displaystyle 10\)\(\displaystyle 15\), __________ 

Possible Answers:

\(\displaystyle 21\)

\(\displaystyle 20\)

\(\displaystyle 25\)

\(\displaystyle 22\)

\(\displaystyle 23\)

Correct answer:

\(\displaystyle 20\)

Explanation:

In this series we are adding \(\displaystyle 5\) each time, or counting by \(\displaystyle 5\). \(\displaystyle 5+5=10\), \(\displaystyle 10+5=15\)\(\displaystyle 15+5=20\).

Example Question #12 : Adding And Subtracting Within 20

Fill in the blank \(\displaystyle 3\), \(\displaystyle 6\), __________\(\displaystyle 12\), \(\displaystyle 15\) 

Possible Answers:

\(\displaystyle 8\)

\(\displaystyle 9\)

\(\displaystyle 7\)

\(\displaystyle 11\)

\(\displaystyle 10\)

Correct answer:

\(\displaystyle 9\)

Explanation:

Explanation: In this series we are adding \(\displaystyle 3\) each time, or counting by \(\displaystyle 3\)\(\displaystyle 3+3=6\)\(\displaystyle 6+3=9\)\(\displaystyle 9+3=12\), and \(\displaystyle 12+3=15\)

Example Question #12 : Adding And Subtracting Within 20

Fill in the blank: \(\displaystyle 20\), \(\displaystyle 15\), \(\displaystyle 10\),  __________

 

Possible Answers:

\(\displaystyle 3\)

\(\displaystyle 6\)

\(\displaystyle 5\)

\(\displaystyle 1\)

\(\displaystyle 0\)

Correct answer:

\(\displaystyle 5\)

Explanation:

In this series we are subtracting \(\displaystyle 5\), or counting down by \(\displaystyle 5\)\(\displaystyle 20-5=15\)\(\displaystyle 15-5=10\), and \(\displaystyle 10-5=5\).

Example Question #111 : Common Core Math: Grade 1

Fill in the blank: \(\displaystyle 10\), \(\displaystyle 8\),__________, \(\displaystyle 4\), \(\displaystyle 2\) 

Possible Answers:

\(\displaystyle 5\)

\(\displaystyle 7\)

\(\displaystyle 10\)

\(\displaystyle 4\)

\(\displaystyle 6\)

Correct answer:

\(\displaystyle 6\)

Explanation:

In this series we are subtracting by \(\displaystyle 2\), or counting down by \(\displaystyle 2\). \(\displaystyle 10-2=8\), \(\displaystyle 8-2=6\), \(\displaystyle 6-2=4\), and \(\displaystyle 4-2=2\).

Example Question #13 : Adding And Subtracting Within 20

Fill in the blank: \(\displaystyle 20\), \(\displaystyle 16\), __________, \(\displaystyle 8\), \(\displaystyle 4\) 

 

Possible Answers:

\(\displaystyle 14\)

\(\displaystyle 15\)

\(\displaystyle 9\)

\(\displaystyle 12\)

\(\displaystyle 13\)

Correct answer:

\(\displaystyle 12\)

Explanation:

In this series we are subtracting \(\displaystyle 4\), or counting down by \(\displaystyle 4\)\(\displaystyle 20-4=16\)\(\displaystyle 16-4=12\)\(\displaystyle 12-4=8\), and \(\displaystyle 8-4=4\).

Example Question #14 : Adding And Subtracting Within 20

Fill in the blank: \(\displaystyle 10\), __________, \(\displaystyle 6\), \(\displaystyle 4\), \(\displaystyle 2\) 

 

Possible Answers:

\(\displaystyle 5\)

\(\displaystyle 7\)

\(\displaystyle 12\)

\(\displaystyle 8\)

\(\displaystyle 9\)

Correct answer:

\(\displaystyle 8\)

Explanation:

In this series we are subtracting by \(\displaystyle 2\), or counting down by \(\displaystyle 2\)\(\displaystyle 10-2=8\), \(\displaystyle 8-2=6\), \(\displaystyle 6-2=4\), and \(\displaystyle 4-2=2\).

Example Question #114 : Common Core Math: Grade 1

Fill in the blank: \(\displaystyle 15\), __________, \(\displaystyle 9\), \(\displaystyle 6\)\(\displaystyle 3\)

Possible Answers:

\(\displaystyle 20\)

\(\displaystyle 18\)

\(\displaystyle 12\)

\(\displaystyle 14\)

\(\displaystyle 13\)

Correct answer:

\(\displaystyle 12\)

Explanation:

In this series we are subtracting \(\displaystyle 3\), or counting down by \(\displaystyle 3\)\(\displaystyle 15-3=12\)\(\displaystyle 12-3=9\)\(\displaystyle 9-3=6\), and \(\displaystyle 6-3=3\).

Example Question #115 : Common Core Math: Grade 1

Fill in the blank: \(\displaystyle 20\), __________, \(\displaystyle 12\), \(\displaystyle 8\), \(\displaystyle 4\)

 

Possible Answers:

\(\displaystyle 16\)

\(\displaystyle 14\)

\(\displaystyle 17\)

\(\displaystyle 18\)

\(\displaystyle 15\)

Correct answer:

\(\displaystyle 16\)

Explanation:

In this series we are subtracting \(\displaystyle 4\), or counting down by \(\displaystyle 4\)\(\displaystyle 20-4=16\), \(\displaystyle 16-4=12\), \(\displaystyle 12-4=8\), and \(\displaystyle 8-4=4\).

Example Question #116 : Common Core Math: Grade 1

Fill in the blank: \(\displaystyle 10\), \(\displaystyle 8\), \(\displaystyle 6\), __________, \(\displaystyle 2\) 

 

Possible Answers:

\(\displaystyle 0\)

\(\displaystyle 5\)

\(\displaystyle 3\)

\(\displaystyle 4\)

\(\displaystyle 1\)

Correct answer:

\(\displaystyle 4\)

Explanation:

In this series we are subtracting by \(\displaystyle 2\), or counting down by \(\displaystyle 2\)\(\displaystyle 10-2=8\)\(\displaystyle 8-2=6\)\(\displaystyle 6-2=4\), and \(\displaystyle 4-2=2\).

Example Question #117 : Common Core Math: Grade 1

Fill in the blank: \(\displaystyle 15\), \(\displaystyle 12\), \(\displaystyle 9\), __________, \(\displaystyle 3\)

 

Possible Answers:

\(\displaystyle 1\)

\(\displaystyle 4\)

\(\displaystyle 8\)

\(\displaystyle 7\)

\(\displaystyle 6\)

Correct answer:

\(\displaystyle 6\)

Explanation:

In this series we are subtracting \(\displaystyle 3\), or counting down by \(\displaystyle 3\)\(\displaystyle 15-3=12\)\(\displaystyle 12-3=9\)\(\displaystyle 9-3=6\), and \(\displaystyle 6-3=3\).

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