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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 350 · 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 22 and take away the sum of its digits. What do you get?
  2. 2.?254 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 24 and take away the sum of its digits. What do you get?
  4. 4.Take 43 and take away the sum of its digits. What do you get?
  5. 5.Take 53 and take away the sum of its digits. What do you get?
  6. 6.?349 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.7?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 71 and take away the sum of its digits. What do you get?
  9. 9.Take 77 and take away the sum of its digits. What do you get?
  10. 10.5?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.2?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 68 and take away the sum of its digits. What do you get?
  13. 13.210? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?808 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 62 and take away the sum of its digits. What do you get?
  16. 16.1?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.362? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 11 and take away the sum of its digits. What do you get?
  19. 19.?730 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 18 and take away the sum of its digits. What do you get?
  21. 21.?977 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 45 and take away the sum of its digits. What do you get?
  23. 23.5?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.727? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 42 and take away the sum of its digits. What do you get?
  26. 26.Take 12 and take away the sum of its digits. What do you get?
  27. 27.?811 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 20 and take away the sum of its digits. What do you get?
  29. 29.74? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.848? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.589? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.356? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?573 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.1?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.6?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?718 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 83 and take away the sum of its digits. What do you get?
  38. 38.16?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 32 and take away the sum of its digits. What do you get?
  40. 40.?818 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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