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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 471 · 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. 1.49?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?026 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.44?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 72 and take away the sum of its digits. What do you get?
  5. 5.6?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.75?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?074 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.5?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 90 and take away the sum of its digits. What do you get?
  10. 10.710? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.341? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.641? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?994 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 11 and take away the sum of its digits. What do you get?
  15. 15.36?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 82 and take away the sum of its digits. What do you get?
  17. 17.?664 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?381 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 28 and take away the sum of its digits. What do you get?
  20. 20.35?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.186? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.50?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?541 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.43?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 98 and take away the sum of its digits. What do you get?
  26. 26.Take 27 and take away the sum of its digits. What do you get?
  27. 27.?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.716? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.540? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.6?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.7?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 41 and take away the sum of its digits. What do you get?
  34. 34.?163 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 32 and take away the sum of its digits. What do you get?
  36. 36.1?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 56 and take away the sum of its digits. What do you get?
  38. 38.401? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.22?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 84 and take away the sum of its digits. What do you get?

Answer key

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

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