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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 279 · 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. 1.690? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.65?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.725? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 40 and take away the sum of its digits. What do you get?
  5. 5.Take 64 and take away the sum of its digits. What do you get?
  6. 6.Take 83 and take away the sum of its digits. What do you get?
  7. 7.22?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.72? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.19?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 20 and take away the sum of its digits. What do you get?
  11. 11.545? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 51 and take away the sum of its digits. What do you get?
  13. 13.3?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.51?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.1?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?941 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?228 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 81 and take away the sum of its digits. What do you get?
  19. 19.4?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?331 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 62 and take away the sum of its digits. What do you get?
  22. 22.Take 97 and take away the sum of its digits. What do you get?
  23. 23.Take 99 and take away the sum of its digits. What do you get?
  24. 24.503? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?095 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.78?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?418 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.351? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 66 and take away the sum of its digits. What do you get?
  30. 30.Take 47 and take away the sum of its digits. What do you get?
  31. 31.1?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?410 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 79 and take away the sum of its digits. What do you get?
  34. 34.?31 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.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.194? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.2?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 24 and take away the sum of its digits. What do you get?
  40. 40.6?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 3
  2. 5
  3. 4
  4. 36
  5. 54
  6. 72
  7. 7
  8. 9
  9. 2
  10. 18
  11. 4
  12. 45
  13. 8
  14. 1
  15. 1
  16. 4
  17. 6
  18. 72
  19. 5
  20. 2
  21. 54
  22. 81
  23. 81
  24. 1
  25. 4
  26. 6
  27. 5
  28. 9
  29. 54
  30. 36
  31. 2
  32. 4
  33. 63
  34. 5
  35. 81
  36. 7
  37. 4
  38. 2
  39. 18
  40. 2

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