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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 988 · 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 34 and take away the sum of its digits. What do you get?
  2. 2.Take 74 and take away the sum of its digits. What do you get?
  3. 3.?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.230? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 86 and take away the sum of its digits. What do you get?
  6. 6.2?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.78?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 77 and take away the sum of its digits. What do you get?
  9. 9.?523 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.7?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?662 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 70 and take away the sum of its digits. What do you get?
  13. 13.?154 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.6?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 85 and take away the sum of its digits. What do you get?
  17. 17.?123 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 29 and take away the sum of its digits. What do you get?
  19. 19.?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.6?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?195 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.374? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?516 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.5?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.80?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.83?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 55 and take away the sum of its digits. What do you get?
  28. 28.Take 92 and take away the sum of its digits. What do you get?
  29. 29.Take 79 and take away the sum of its digits. What do you get?
  30. 30.Take 28 and take away the sum of its digits. What do you get?
  31. 31.?411 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.67?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.48? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.25?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.2?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.404? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.684? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.460? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.12?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 30 and take away the sum of its digits. What do you get?

Answer key

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

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