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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 391 · 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 70 and take away the sum of its digits. What do you get?
  2. 2.7?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?920 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.305? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.402? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 33 and take away the sum of its digits. What do you get?
  7. 7.778? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.26?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.5?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.60?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 30 and take away the sum of its digits. What do you get?
  12. 12.Take 29 and take away the sum of its digits. What do you get?
  13. 13.30?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.282? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 24 and take away the sum of its digits. What do you get?
  16. 16.Take 38 and take away the sum of its digits. What do you get?
  17. 17.80? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 25 and take away the sum of its digits. What do you get?
  19. 19.Take 73 and take away the sum of its digits. What do you get?
  20. 20.Take 61 and take away the sum of its digits. What do you get?
  21. 21.Take 34 and take away the sum of its digits. What do you get?
  22. 22.Take 93 and take away the sum of its digits. What do you get?
  23. 23.418? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.64?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 27 and take away the sum of its digits. What do you get?
  26. 26.37?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?707 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?843 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 58 and take away the sum of its digits. What do you get?
  30. 30.?215 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 44 and take away the sum of its digits. What do you get?
  32. 32.203? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.3?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?979 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.148? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.562? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?021 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 54 and take away the sum of its digits. What do you get?
  39. 39.134? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.877? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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