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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 928 · 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.?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 13 and take away the sum of its digits. What do you get?
  3. 3.2?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?584 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.7?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 19 and take away the sum of its digits. What do you get?
  7. 7.?208 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.795? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 83 and take away the sum of its digits. What do you get?
  10. 10.Take 93 and take away the sum of its digits. What do you get?
  11. 11.Take 17 and take away the sum of its digits. What do you get?
  12. 12.60? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.3?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.7?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.7?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.84?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 49 and take away the sum of its digits. What do you get?
  18. 18.51? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 18 and take away the sum of its digits. What do you get?
  21. 21.Take 12 and take away the sum of its digits. What do you get?
  22. 22.Take 54 and take away the sum of its digits. What do you get?
  23. 23.865? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 11 and take away the sum of its digits. What do you get?
  25. 25.Take 28 and take away the sum of its digits. What do you get?
  26. 26.813? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.78? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.4?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.18?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 72 and take away the sum of its digits. What do you get?
  31. 31.250? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.1?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.65?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.36?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.196? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.28?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 50 and take away the sum of its digits. What do you get?
  38. 38.?952 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.44? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.638? 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. 9
  3. 8
  4. 1
  5. 7
  6. 9
  7. 8
  8. 6
  9. 72
  10. 81
  11. 9
  12. 3
  13. 3
  14. 9
  15. 9
  16. 2
  17. 36
  18. 3
  19. 9
  20. 9
  21. 9
  22. 45
  23. 8
  24. 9
  25. 18
  26. 6
  27. 3
  28. 5
  29. 3
  30. 63
  31. 2
  32. 9
  33. 1
  34. 8
  35. 2
  36. 9
  37. 45
  38. 2
  39. 1
  40. 1

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