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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 797 · 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. 1.2?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 58 and take away the sum of its digits. What do you get?
  3. 3.Take 79 and take away the sum of its digits. What do you get?
  4. 4.87?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.16?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.55?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 93 and take away the sum of its digits. What do you get?
  8. 8.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.57?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 47 and take away the sum of its digits. What do you get?
  11. 11.2?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.7?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 90 and take away the sum of its digits. What do you get?
  14. 14.Take 69 and take away the sum of its digits. What do you get?
  15. 15.Take 17 and take away the sum of its digits. What do you get?
  16. 16.Take 67 and take away the sum of its digits. What do you get?
  17. 17.2?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.64?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.779? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 18 and take away the sum of its digits. What do you get?
  22. 22.?587 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?152 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.73?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 62 and take away the sum of its digits. What do you get?
  26. 26.Take 45 and take away the sum of its digits. What do you get?
  27. 27.?292 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 80 and take away the sum of its digits. What do you get?
  29. 29.45?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.46?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 77 and take away the sum of its digits. What do you get?
  32. 32.832? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.285? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?514 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 55 and take away the sum of its digits. What do you get?
  36. 36.?151 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 24 and take away the sum of its digits. What do you get?
  38. 38.Take 20 and take away the sum of its digits. What do you get?
  39. 39.Take 15 and take away the sum of its digits. What do you get?
  40. 40.51?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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