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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 887 · 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 73 and take away the sum of its digits. What do you get?
  2. 2.822? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.66? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?300 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 83 and take away the sum of its digits. What do you get?
  6. 6.?498 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 78 and take away the sum of its digits. What do you get?
  8. 8.Take 26 and take away the sum of its digits. What do you get?
  9. 9.Take 62 and take away the sum of its digits. What do you get?
  10. 10.464? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.98? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.554? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.497? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 70 and take away the sum of its digits. What do you get?
  15. 15.1?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 80 and take away the sum of its digits. What do you get?
  17. 17.Take 16 and take away the sum of its digits. What do you get?
  18. 18.1?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 49 and take away the sum of its digits. What do you get?
  20. 20.71?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.60?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.350? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.181? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 30 and take away the sum of its digits. What do you get?
  25. 25.Take 79 and take away the sum of its digits. What do you get?
  26. 26.506? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?815 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.4?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.130? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?303 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?632 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.1?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 35 and take away the sum of its digits. What do you get?
  35. 35.127? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 96 and take away the sum of its digits. What do you get?
  37. 37.Take 94 and take away the sum of its digits. What do you get?
  38. 38.Take 89 and take away the sum of its digits. What do you get?
  39. 39.?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 21 and take away the sum of its digits. What do you get?

Answer key

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

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