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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 291 · 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.?355 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.7?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?589 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 94 and take away the sum of its digits. What do you get?
  5. 5.735? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.6?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.6?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.49?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.541? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.275? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.20?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 81 and take away the sum of its digits. What do you get?
  15. 15.Take 20 and take away the sum of its digits. What do you get?
  16. 16.Take 36 and take away the sum of its digits. What do you get?
  17. 17.Take 49 and take away the sum of its digits. What do you get?
  18. 18.?787 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.647? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 99 and take away the sum of its digits. What do you get?
  21. 21.?568 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 98 and take away the sum of its digits. What do you get?
  23. 23.?634 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.20? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?980 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.27?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.77?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?354 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.706? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 90 and take away the sum of its digits. What do you get?
  32. 32.Take 69 and take away the sum of its digits. What do you get?
  33. 33.75?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?001 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 48 and take away the sum of its digits. What do you get?
  36. 36.Take 84 and take away the sum of its digits. What do you get?
  37. 37.Take 23 and take away the sum of its digits. What do you get?
  38. 38.?574 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.208? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?266 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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