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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 541 · 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 25 and take away the sum of its digits. What do you get?
  2. 2.?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.774? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?282 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?629 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 27 and take away the sum of its digits. What do you get?
  7. 7.?088 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?079 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?503 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?816 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.104? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.83?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.10?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.7?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?667 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.787? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.3?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.810? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.83?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?817 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.30?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 56 and take away the sum of its digits. What do you get?
  24. 24.6?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 86 and take away the sum of its digits. What do you get?
  26. 26.?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.614? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 37 and take away the sum of its digits. What do you get?
  29. 29.Take 52 and take away the sum of its digits. What do you get?
  30. 30.Take 75 and take away the sum of its digits. What do you get?
  31. 31.?803 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 32 and take away the sum of its digits. What do you get?
  33. 33.Take 74 and take away the sum of its digits. What do you get?
  34. 34.4?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.80? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?613 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 30 and take away the sum of its digits. What do you get?
  38. 38.?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.6?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 19 and take away the sum of its digits. What do you get?

Answer key

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

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