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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 994 · 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 13 and take away the sum of its digits. What do you get?
  2. 2.Take 32 and take away the sum of its digits. What do you get?
  3. 3.Take 44 and take away the sum of its digits. What do you get?
  4. 4.Take 94 and take away the sum of its digits. What do you get?
  5. 5.621? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.55?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 75 and take away the sum of its digits. What do you get?
  8. 8.8?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?322 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.6?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?044 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.600? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?410 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.28?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.282? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 61 and take away the sum of its digits. What do you get?
  17. 17.Take 37 and take away the sum of its digits. What do you get?
  18. 18.Take 12 and take away the sum of its digits. What do you get?
  19. 19.412? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 97 and take away the sum of its digits. What do you get?
  21. 21.589? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 21 and take away the sum of its digits. What do you get?
  23. 23.35?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 53 and take away the sum of its digits. What do you get?
  25. 25.?455 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 85 and take away the sum of its digits. What do you get?
  27. 27.2?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.7?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 77 and take away the sum of its digits. What do you get?
  30. 30.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.15?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 51 and take away the sum of its digits. What do you get?
  33. 33.Take 19 and take away the sum of its digits. What do you get?
  34. 34.?673 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.334? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 88 and take away the sum of its digits. What do you get?
  37. 37.6?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 81 and take away the sum of its digits. What do you get?
  39. 39.6?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 50 and take away the sum of its digits. What do you get?

Answer key

  1. 9
  2. 27
  3. 36
  4. 81
  5. 9
  6. 2
  7. 63
  8. 8
  9. 2
  10. 6
  11. 1
  12. 3
  13. 4
  14. 3
  15. 6
  16. 54
  17. 27
  18. 9
  19. 2
  20. 81
  21. 5
  22. 18
  23. 1
  24. 45
  25. 4
  26. 72
  27. 1
  28. 8
  29. 63
  30. 7
  31. 3
  32. 45
  33. 9
  34. 2
  35. 8
  36. 72
  37. 1
  38. 72
  39. 4
  40. 45

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