MENTAL ARITHMETIC: SUBTRACTION

PROBLEMS

Do the problem yourself first!

11.  Explain why  41 − 35 = 6.

Because 35 plus 6 is 41.

12.  Practice the following.  Do not count on your fingers

 2 + 7 = 9. 1 + 5 = 6. 2 + 3 = 5. 2 + 6 = 8. 3 + 4 = 7. 5 + 4 = 9. 3 + 2 = 5. 1 + 7 = 8. 5 + 3 = 8. 1 + 4 = 5. 5 + 2 = 7. 6 + 3 = 9. 4 + 3 = 7. 4 + 5 = 9. 2 + 2 = 4. 3 + 3 = 6. 1 + 8 = 9. 1 + 5 = 6. 1 + 2 = 3. 3 + 5 = 8.

13.  Calculate each column mentally by adding to the smaller number.

 8 − 5 = 3 90 − 60 = 30 95 − 40 = 55 43 − 20 = 23 80 − 50 = 30 80 − 30 = 50 63 − 10 = 53 78 − 20 = 58 825 − 500 = 325 84 − 30 = 54 62 − 30 = 32 94 − 30 = 64 95 − 70 = 25 72 − 50 = 22 48 − 30 = 18 81 − 40 = 41 99 − 20 = 79 66 − 50 = 16

14.  What number must you add?

 8 + 6 = 14. 8 + 5 = 13. 7 + 9 = 16. 8 + 3 = 11. 2 + 9 = 11. 4 + 8 = 12. 9 + 8 = 17. 7 + 6 = 13. 5 + 7 = 12. 9 + 7 = 16. 6 + 5 = 11. 5 + 6 = 11. 6 + 9 = 15. 5 + 9 = 14. 5 + 8 = 13. 8 + 9 = 17. 9 + 4 = 13. 6 + 6 = 12. 8 + 7 = 15. 6 + 8 = 14. 7 + 5 = 12. 4 + 9 = 13. 9 + 3 = 12. 4 + 7 = 11. 3 + 8 = 11. 7 + 8 = 15. 9 + 2 = 11. 8 + 4 = 12. 6 + 7 = 13. 7 + 4 = 11. 9 + 5 = 14. 3 + 9 = 12.

15.  What number must you add to the smaller number?

 120 − 90 = 30 1900 − 1200 = 700 126 − 90 = 36 1800 − 1400 = 400 135 − 90 = 45 1842 − 1400 = 442 124 − 80 = 44 1986 − 1600 = 386 138 − 80 = 58 2004 − 1500 = 504 146 − 80 = 66 2110 − 1700 = 410

The complement to 10

 6. 3 + 7 = 10 9 + 1 = 10 4 + 6 = 10 2 + 8 = 10 1 + 9 = 10 8 + 2 = 10 6 + 4 = 10 5 + 5 = 10 7 + 3 = 10

17.  More complements to 10.

 30 − 2 = 28 40 − 6 = 34 50 − 3 = 47 60 − 9 = 51 40 − 5 = 35 50 − 1 = 49 80 − 4 = 76 90 − 4 = 86 50 − 9 = 41 70 − 4 = 66 20 − 3 = 17 50 − 7 = 43 20 − 6 = 14 30 − 5 = 25 70 − 8 = 62 20 − 9 = 11

*     *     *

 100 − 3 = 97 220 − 1 = 219 100 − 7 = 93 350 − 3 = 347 110 − 6 = 104 590 − 7 = 583 120 − 8 = 112 600 − 5 = 595 130 − 5 = 125 700 − 2 = 698

18.  Calculate mentally.

 \$4.00 − 3¢ = \$3.97 \$7.00 − 8¢ = \$6.92 \$8.00 − 9¢ = \$7.91 \$9.00 − 6¢ = \$8.94 \$1.00 − 4¢ = \$.96 \$6.00 − 7¢ = \$5.93

19.  Subtracting a one-digit number.  Break off from the smaller
19.  number the ones digit of the larger, and subtract.  Then subtract the
19.  rest of the smaller number.

Illustrate that in writing.

61 − 3 = 61 − 1 − 2 = 60 − 2 = 58

93 − 4 = 93 − 3 − 1 = 90 − 1 = 89

10.  Calculate mentally.

 22 − 3 = 19 61 − 2 = 59 71 − 4 = 67 53 − 4 = 49 83 − 5 = 78 22 − 4 = 18 31 − 3 = 28 62 − 5 = 57 91 − 2 = 89 21 − 4 = 17 42 − 3 = 39 92 − 4 = 88 43 − 5  = 38 72 − 4 = 68 52 − 5 = 47 73 − 4 = 69 24 − 5 = 19 44 − 5 = 39

Continue on to the next section.

or
The text passage contains a series of arithmetic problems and their solutions, primarily focusing on subtraction and addition. Each problem is followed by its solution, and the problems are structured in a way that encourages mental calculation.
multiple_questions_with_answers
Given a text passage, determine:
    1. If it contains a mathematical question (including word problems or calculations)
    2. If an answer to that mathematical question is provided in the text

First, describe the content structure you found in 1-2 sentences.

Then provide your analysis in the following format:
TYPE: <one of the following values>
- NO_QUESTION
- SINGLE_QUESTION
- SINGLE_QUESTION_WITH_ANSWER
- MULTIPLE_QUESTIONS
- MULTIPLE_QUESTIONS_WITH_ANSWERS
system
MENTAL ARITHMETIC: SUBTRACTION

PROBLEMS

Do the problem yourself first!

11.  Explain why  41 − 35 = 6.

Because 35 plus 6 is 41.

12.  Practice the following.  Do not count on your fingers

 2 + 7 = 9. 1 + 5 = 6. 2 + 3 = 5. 2 + 6 = 8. 3 + 4 = 7. 5 + 4 = 9. 3 + 2 = 5. 1 + 7 = 8. 5 + 3 = 8. 1 + 4 = 5. 5 + 2 = 7. 6 + 3 = 9. 4 + 3 = 7. 4 + 5 = 9. 2 + 2 = 4. 3 + 3 = 6. 1 + 8 = 9. 1 + 5 = 6. 1 + 2 = 3. 3 + 5 = 8.

13.  Calculate each column mentally by adding to the smaller number.

 8 − 5 = 3 90 − 60 = 30 95 − 40 = 55 43 − 20 = 23 80 − 50 = 30 80 − 30 = 50 63 − 10 = 53 78 − 20 = 58 825 − 500 = 325 84 − 30 = 54 62 − 30 = 32 94 − 30 = 64 95 − 70 = 25 72 − 50 = 22 48 − 30 = 18 81 − 40 = 41 99 − 20 = 79 66 − 50 = 16

14.  What number must you add?

 8 + 6 = 14. 8 + 5 = 13. 7 + 9 = 16. 8 + 3 = 11. 2 + 9 = 11. 4 + 8 = 12. 9 + 8 = 17. 7 + 6 = 13. 5 + 7 = 12. 9 + 7 = 16. 6 + 5 = 11. 5 + 6 = 11. 6 + 9 = 15. 5 + 9 = 14. 5 + 8 = 13. 8 + 9 = 17. 9 + 4 = 13. 6 + 6 = 12. 8 + 7 = 15. 6 + 8 = 14. 7 + 5 = 12. 4 + 9 = 13. 9 + 3 = 12. 4 + 7 = 11. 3 + 8 = 11. 7 + 8 = 15. 9 + 2 = 11. 8 + 4 = 12. 6 + 7 = 13. 7 + 4 = 11. 9 + 5 = 14. 3 + 9 = 12.

15.  What number must you add to the smaller number?

 120 − 90 = 30 1900 − 1200 = 700 126 − 90 = 36 1800 − 1400 = 400 135 − 90 = 45 1842 − 1400 = 442 124 − 80 = 44 1986 − 1600 = 386 138 − 80 = 58 2004 − 1500 = 504 146 − 80 = 66 2110 − 1700 = 410

The complement to 10

 6. 3 + 7 = 10 9 + 1 = 10 4 + 6 = 10 2 + 8 = 10 1 + 9 = 10 8 + 2 = 10 6 + 4 = 10 5 + 5 = 10 7 + 3 = 10

17.  More complements to 10.

 30 − 2 = 28 40 − 6 = 34 50 − 3 = 47 60 − 9 = 51 40 − 5 = 35 50 − 1 = 49 80 − 4 = 76 90 − 4 = 86 50 − 9 = 41 70 − 4 = 66 20 − 3 = 17 50 − 7 = 43 20 − 6 = 14 30 − 5 = 25 70 − 8 = 62 20 − 9 = 11

*     *     *

 100 − 3 = 97 220 − 1 = 219 100 − 7 = 93 350 − 3 = 347 110 − 6 = 104 590 − 7 = 583 120 − 8 = 112 600 − 5 = 595 130 − 5 = 125 700 − 2 = 698

18.  Calculate mentally.

 \$4.00 − 3¢ = \$3.97 \$7.00 − 8¢ = \$6.92 \$8.00 − 9¢ = \$7.91 \$9.00 − 6¢ = \$8.94 \$1.00 − 4¢ = \$.96 \$6.00 − 7¢ = \$5.93

19.  Subtracting a one-digit number.  Break off from the smaller
19.  number the ones digit of the larger, and subtract.  Then subtract the
19.  rest of the smaller number.

Illustrate that in writing.

61 − 3 = 61 − 1 − 2 = 60 − 2 = 58

93 − 4 = 93 − 3 − 1 = 90 − 1 = 89

10.  Calculate mentally.

 22 − 3 = 19 61 − 2 = 59 71 − 4 = 67 53 − 4 = 49 83 − 5 = 78 22 − 4 = 18 31 − 3 = 28 62 − 5 = 57 91 − 2 = 89 21 − 4 = 17 42 − 3 = 39 92 − 4 = 88 43 − 5  = 38 72 − 4 = 68 52 − 5 = 47 73 − 4 = 69 24 − 5 = 19 44 − 5 = 39

Continue on to the next section.

or
user
The text passage contains a series of arithmetic problems and their solutions, primarily focusing on subtraction and addition. Each problem is followed by its solution, and the problems are structured in a way that encourages mental calculation.

TYPE: MULTIPLE_QUESTIONS_WITH_ANSWERS