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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 202 · 40 questions
TalentJR

The trick (Digits add to the 9 table): Add the digits you can see. Find the next number in the 9 table (9, 18, 27 …) above that total. The hidden digit is the difference. (Any number minus its digit sum is in the 9 table too.)

NameDateTime takenScore ___ / 40
  1. 1.Take 80 and take away the sum of its digits. What do you get?
  2. 2.90? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 40 and take away the sum of its digits. What do you get?
  4. 4.4?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?665 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.1?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.1?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?862 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?431 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 41 and take away the sum of its digits. What do you get?
  11. 11.?436 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.61?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 97 and take away the sum of its digits. What do you get?
  14. 14.Take 85 and take away the sum of its digits. What do you get?
  15. 15.77?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 71 and take away the sum of its digits. What do you get?
  17. 17.?753 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.1?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.1?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.87?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?167 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.120? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 66 and take away the sum of its digits. What do you get?
  25. 25.?182 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 28 and take away the sum of its digits. What do you get?
  27. 27.?530 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.1?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?856 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.7?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?572 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.75?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 54 and take away the sum of its digits. What do you get?
  34. 34.?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?685 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 19 and take away the sum of its digits. What do you get?
  37. 37.Take 79 and take away the sum of its digits. What do you get?
  38. 38.?784 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.532? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 77 and take away the sum of its digits. What do you get?

Answer key

  1. 72
  2. 9
  3. 36
  4. 8
  5. 1
  6. 9
  7. 5
  8. 2
  9. 1
  10. 36
  11. 5
  12. 7
  13. 81
  14. 72
  15. 9
  16. 63
  17. 3
  18. 4
  19. 4
  20. 5
  21. 7
  22. 4
  23. 6
  24. 54
  25. 7
  26. 18
  27. 1
  28. 5
  29. 8
  30. 9
  31. 4
  32. 4
  33. 45
  34. 1
  35. 8
  36. 9
  37. 63
  38. 8
  39. 8
  40. 63

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