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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 48 · 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. 1.7?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.8?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.85?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.2?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?293 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 99 and take away the sum of its digits. What do you get?
  7. 7.64?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 95 and take away the sum of its digits. What do you get?
  9. 9.6?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.830? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 56 and take away the sum of its digits. What do you get?
  12. 12.Take 52 and take away the sum of its digits. What do you get?
  13. 13.28?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.397? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.35?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 35 and take away the sum of its digits. What do you get?
  17. 17.Take 30 and take away the sum of its digits. What do you get?
  18. 18.3?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?276 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?623 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.410? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.48?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?406 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?490 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?553 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?314 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 79 and take away the sum of its digits. What do you get?
  29. 29.Take 24 and take away the sum of its digits. What do you get?
  30. 30.Take 50 and take away the sum of its digits. What do you get?
  31. 31.Take 61 and take away the sum of its digits. What do you get?
  32. 32.8?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.8?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?880 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?185 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.1?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.646? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 13 and take away the sum of its digits. What do you get?
  40. 40.?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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