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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 420 · 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. 1.5?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 16 and take away the sum of its digits. What do you get?
  3. 3.Take 55 and take away the sum of its digits. What do you get?
  4. 4.5?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.338? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 86 and take away the sum of its digits. What do you get?
  7. 7.?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 40 and take away the sum of its digits. What do you get?
  9. 9.5?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.7?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 76 and take away the sum of its digits. What do you get?
  12. 12.?265 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.346? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.2?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.369? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?119 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 98 and take away the sum of its digits. What do you get?
  18. 18.68?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.756? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.19?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.584? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.7?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?870 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.852? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.113? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.15?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 22 and take away the sum of its digits. What do you get?
  30. 30.?365 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 25 and take away the sum of its digits. What do you get?
  32. 32.65?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?209 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 19 and take away the sum of its digits. What do you get?
  35. 35.?421 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.6?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.155? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?238 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.67? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?31 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. 45
  4. 3
  5. 4
  6. 72
  7. 5
  8. 36
  9. 6
  10. 2
  11. 63
  12. 5
  13. 5
  14. 5
  15. 9
  16. 7
  17. 81
  18. 7
  19. 9
  20. 8
  21. 8
  22. 1
  23. 6
  24. 5
  25. 3
  26. 3
  27. 4
  28. 3
  29. 18
  30. 4
  31. 18
  32. 6
  33. 7
  34. 9
  35. 2
  36. 6
  37. 7
  38. 5
  39. 5
  40. 5

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