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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 265 · 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 95 and take away the sum of its digits. What do you get?
  2. 2.?670 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.2?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 25 and take away the sum of its digits. What do you get?
  5. 5.Take 72 and take away the sum of its digits. What do you get?
  6. 6.4?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?971 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?517 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 44 and take away the sum of its digits. What do you get?
  10. 10.Take 13 and take away the sum of its digits. What do you get?
  11. 11.?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 65 and take away the sum of its digits. What do you get?
  13. 13.Take 99 and take away the sum of its digits. What do you get?
  14. 14.Take 98 and take away the sum of its digits. What do you get?
  15. 15.Take 19 and take away the sum of its digits. What do you get?
  16. 16.?478 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.856? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.5?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.70?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.3?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.94? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 73 and take away the sum of its digits. What do you get?
  23. 23.380? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.65?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.170? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.82?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?258 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.40?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 74 and take away the sum of its digits. What do you get?
  31. 31.91? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.9?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?025 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.1?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.38?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.78? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?246 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.56?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 64 and take away the sum of its digits. What do you get?
  40. 40.367? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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