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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 880 · 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 16 and take away the sum of its digits. What do you get?
  2. 2.370? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.2?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.161? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?050 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.487? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 35 and take away the sum of its digits. What do you get?
  8. 8.Take 58 and take away the sum of its digits. What do you get?
  9. 9.Take 45 and take away the sum of its digits. What do you get?
  10. 10.Take 12 and take away the sum of its digits. What do you get?
  11. 11.553? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.7?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 26 and take away the sum of its digits. What do you get?
  14. 14.13?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 69 and take away the sum of its digits. What do you get?
  16. 16.19?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.36?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.618? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.136? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 89 and take away the sum of its digits. What do you get?
  21. 21.Take 42 and take away the sum of its digits. What do you get?
  22. 22.Take 19 and take away the sum of its digits. What do you get?
  23. 23.Take 96 and take away the sum of its digits. What do you get?
  24. 24.5?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?232 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 50 and take away the sum of its digits. What do you get?
  27. 27.43?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.8?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.12?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.54?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.58?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.3?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.35?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.52?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?838 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.70?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.35?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.6?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.220? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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