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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 755 · 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.?821 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 81 and take away the sum of its digits. What do you get?
  3. 3.Take 40 and take away the sum of its digits. What do you get?
  4. 4.?128 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 30 and take away the sum of its digits. What do you get?
  6. 6.?829 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?965 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.631? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 31 and take away the sum of its digits. What do you get?
  10. 10.32?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 24 and take away the sum of its digits. What do you get?
  12. 12.1?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 85 and take away the sum of its digits. What do you get?
  14. 14.196? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?070 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 56 and take away the sum of its digits. What do you get?
  17. 17.Take 27 and take away the sum of its digits. What do you get?
  18. 18.4?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.34?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.248? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.401? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.398? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.800? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.130? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?798 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 51 and take away the sum of its digits. What do you get?
  27. 27.Take 62 and take away the sum of its digits. What do you get?
  28. 28.228? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?165 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?500 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 13 and take away the sum of its digits. What do you get?
  32. 32.?098 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 57 and take away the sum of its digits. What do you get?
  34. 34.?140 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.2?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.201? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?060 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.6?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.6?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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