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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 508 · 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 31 and take away the sum of its digits. What do you get?
  2. 2.Take 81 and take away the sum of its digits. What do you get?
  3. 3.Take 16 and take away the sum of its digits. What do you get?
  4. 4.203? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 15 and take away the sum of its digits. What do you get?
  6. 6.8?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.4?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.746? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?561 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.705? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.5?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.808? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.692? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.619? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.34?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?188 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 84 and take away the sum of its digits. What do you get?
  18. 18.26?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.2?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?761 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?726 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.7?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.5?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 33 and take away the sum of its digits. What do you get?
  25. 25.Take 12 and take away the sum of its digits. What do you get?
  26. 26.4?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 42 and take away the sum of its digits. What do you get?
  28. 28.145? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?933 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.2?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?809 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 14 and take away the sum of its digits. What do you get?
  33. 33.Take 69 and take away the sum of its digits. What do you get?
  34. 34.Take 68 and take away the sum of its digits. What do you get?
  35. 35.?262 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 71 and take away the sum of its digits. What do you get?
  37. 37.Take 66 and take away the sum of its digits. What do you get?
  38. 38.?422 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 13 and take away the sum of its digits. What do you get?
  40. 40.?501 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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