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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 50 · 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. 1.30? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 66 and take away the sum of its digits. What do you get?
  3. 3.Take 29 and take away the sum of its digits. What do you get?
  4. 4.882? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.204? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.1?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?541 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 18 and take away the sum of its digits. What do you get?
  9. 9.?763 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.34?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?421 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?372 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 31 and take away the sum of its digits. What do you get?
  14. 14.5?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 87 and take away the sum of its digits. What do you get?
  16. 16.Take 84 and take away the sum of its digits. What do you get?
  17. 17.78?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 11 and take away the sum of its digits. What do you get?
  19. 19.Take 46 and take away the sum of its digits. What do you get?
  20. 20.Take 75 and take away the sum of its digits. What do you get?
  21. 21.85?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 49 and take away the sum of its digits. What do you get?
  23. 23.660? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?733 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.1?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 89 and take away the sum of its digits. What do you get?
  27. 27.841? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 95 and take away the sum of its digits. What do you get?
  30. 30.Take 96 and take away the sum of its digits. What do you get?
  31. 31.?060 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?452 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.77?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 94 and take away the sum of its digits. What do you get?
  36. 36.854? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 83 and take away the sum of its digits. What do you get?
  38. 38.21?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?391 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 12 and take away the sum of its digits. What do you get?

Answer key

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

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