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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 338 · 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 44 and take away the sum of its digits. What do you get?
  3. 3.Take 54 and take away the sum of its digits. What do you get?
  4. 4.?033 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.7?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?023 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?014 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.162? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 17 and take away the sum of its digits. What do you get?
  10. 10.Take 37 and take away the sum of its digits. What do you get?
  11. 11.Take 87 and take away the sum of its digits. What do you get?
  12. 12.4?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.700? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.74?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.14?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.9?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 15 and take away the sum of its digits. What do you get?
  18. 18.Take 36 and take away the sum of its digits. What do you get?
  19. 19.Take 50 and take away the sum of its digits. What do you get?
  20. 20.?059 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.298? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.28?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.6?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.27? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.9?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 32 and take away the sum of its digits. What do you get?
  27. 27.247? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 28 and take away the sum of its digits. What do you get?
  29. 29.Take 34 and take away the sum of its digits. What do you get?
  30. 30.1?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.301? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?467 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 88 and take away the sum of its digits. What do you get?
  34. 34.Take 70 and take away the sum of its digits. What do you get?
  35. 35.Take 68 and take away the sum of its digits. What do you get?
  36. 36.Take 11 and take away the sum of its digits. What do you get?
  37. 37.8?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.7?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?842 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?52 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. 36
  3. 45
  4. 3
  5. 8
  6. 4
  7. 4
  8. 9
  9. 9
  10. 27
  11. 72
  12. 3
  13. 2
  14. 5
  15. 8
  16. 8
  17. 9
  18. 27
  19. 45
  20. 4
  21. 8
  22. 5
  23. 3
  24. 9
  25. 9
  26. 27
  27. 5
  28. 18
  29. 27
  30. 3
  31. 5
  32. 1
  33. 72
  34. 63
  35. 54
  36. 9
  37. 2
  38. 8
  39. 4
  40. 2

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