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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 311 · 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 29 and take away the sum of its digits. What do you get?
  2. 2.?572 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.631? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?440 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.433? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.420? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?049 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.4?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?481 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 25 and take away the sum of its digits. What do you get?
  12. 12.39?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?040 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.3?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.7?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 85 and take away the sum of its digits. What do you get?
  17. 17.Take 57 and take away the sum of its digits. What do you get?
  18. 18.1?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 45 and take away the sum of its digits. What do you get?
  20. 20.31?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.365? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 36 and take away the sum of its digits. What do you get?
  23. 23.?736 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.85?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 33 and take away the sum of its digits. What do you get?
  26. 26.Take 14 and take away the sum of its digits. What do you get?
  27. 27.Take 13 and take away the sum of its digits. What do you get?
  28. 28.7?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 35 and take away the sum of its digits. What do you get?
  30. 30.399? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.4?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.3?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.40?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 48 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. 36.7?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?709 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 69 and take away the sum of its digits. What do you get?
  39. 39.?746 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.49?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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