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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 722 · 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 20 and take away the sum of its digits. What do you get?
  2. 2.14?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 78 and take away the sum of its digits. What do you get?
  4. 4.Take 52 and take away the sum of its digits. What do you get?
  5. 5.8?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.7?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?259 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?413 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 11 and take away the sum of its digits. What do you get?
  10. 10.5?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?197 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?201 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?960 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 24 and take away the sum of its digits. What do you get?
  15. 15.45?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.2?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.439? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.5?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 89 and take away the sum of its digits. What do you get?
  20. 20.7?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 75 and take away the sum of its digits. What do you get?
  23. 23.?658 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.1?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 61 and take away the sum of its digits. What do you get?
  26. 26.685? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.78?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?068 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.448? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?645 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.7?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?399 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?649 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?457 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.6?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 60 and take away the sum of its digits. What do you get?
  37. 37.Take 63 and take away the sum of its digits. What do you get?
  38. 38.Take 97 and take away the sum of its digits. What do you get?
  39. 39.743? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 15 and take away the sum of its digits. What do you get?

Answer key

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

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