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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 693 · 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 11 and take away the sum of its digits. What do you get?
  2. 2.Take 61 and take away the sum of its digits. What do you get?
  3. 3.?746 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.23?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 78 and take away the sum of its digits. What do you get?
  6. 6.Take 89 and take away the sum of its digits. What do you get?
  7. 7.8?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.854? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.6?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?737 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.4?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.5?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.57?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.145? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.1?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.27?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 40 and take away the sum of its digits. What do you get?
  18. 18.Take 19 and take away the sum of its digits. What do you get?
  19. 19.Take 44 and take away the sum of its digits. What do you get?
  20. 20.?579 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 85 and take away the sum of its digits. What do you get?
  22. 22.9?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.5?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.48?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 12 and take away the sum of its digits. What do you get?
  26. 26.220? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.18? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 29 and take away the sum of its digits. What do you get?
  29. 29.8?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?542 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.Take 94 and take away the sum of its digits. What do you get?
  33. 33.Take 20 and take away the sum of its digits. What do you get?
  34. 34.10?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?560 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.2?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.396? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 95 and take away the sum of its digits. What do you get?
  39. 39.Take 34 and take away the sum of its digits. What do you get?
  40. 40.788? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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