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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 56 · 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.?160 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?742 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 15 and take away the sum of its digits. What do you get?
  4. 4.1?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 62 and take away the sum of its digits. What do you get?
  6. 6.Take 20 and take away the sum of its digits. What do you get?
  7. 7.225? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?071 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 37 and take away the sum of its digits. What do you get?
  10. 10.78? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?812 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.460? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 45 and take away the sum of its digits. What do you get?
  14. 14.?250 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 46 and take away the sum of its digits. What do you get?
  16. 16.7?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.2?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.12?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 35 and take away the sum of its digits. What do you get?
  20. 20.37? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.18?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 31 and take away the sum of its digits. What do you get?
  23. 23.6?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.6?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 81 and take away the sum of its digits. What do you get?
  26. 26.45?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 96 and take away the sum of its digits. What do you get?
  28. 28.169? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.36?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?920 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.23?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 63 and take away the sum of its digits. What do you get?
  33. 33.29?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?908 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?569 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.1?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?722 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.89? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 75 and take away the sum of its digits. What do you get?
  40. 40.Take 77 and take away the sum of its digits. What do you get?

Answer key

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

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