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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 521 · 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 70 and take away the sum of its digits. What do you get?
  2. 2.708? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.6?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.401? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 65 and take away the sum of its digits. What do you get?
  6. 6.?164 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 95 and take away the sum of its digits. What do you get?
  8. 8.Take 19 and take away the sum of its digits. What do you get?
  9. 9.3?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.2?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.2?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.641? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 58 and take away the sum of its digits. What do you get?
  14. 14.Take 50 and take away the sum of its digits. What do you get?
  15. 15.Take 24 and take away the sum of its digits. What do you get?
  16. 16.21?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.57? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 46 and take away the sum of its digits. What do you get?
  19. 19.22?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?763 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?649 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 92 and take away the sum of its digits. What do you get?
  24. 24.Take 27 and take away the sum of its digits. What do you get?
  25. 25.Take 67 and take away the sum of its digits. What do you get?
  26. 26.Take 25 and take away the sum of its digits. What do you get?
  27. 27.1?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.101? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 15 and take away the sum of its digits. What do you get?
  30. 30.?907 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 31 and take away the sum of its digits. What do you get?
  32. 32.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 75 and take away the sum of its digits. What do you get?
  34. 34.4?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.333? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.2?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 47 and take away the sum of its digits. What do you get?
  38. 38.Take 14 and take away the sum of its digits. What do you get?
  39. 39.Take 48 and take away the sum of its digits. What do you get?
  40. 40.Take 13 and take away the sum of its digits. What do you get?

Answer key

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

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