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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 138 · 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 85 and take away the sum of its digits. What do you get?
  2. 2.4?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?598 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 70 and take away the sum of its digits. What do you get?
  6. 6.4?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.4?19 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.?136 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 80 and take away the sum of its digits. What do you get?
  11. 11.476? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 73 and take away the sum of its digits. What do you get?
  13. 13.Take 89 and take away the sum of its digits. What do you get?
  14. 14.?350 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 68 and take away the sum of its digits. What do you get?
  16. 16.6?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.12?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.77? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?611 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.1?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.63?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?343 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.4?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 49 and take away the sum of its digits. What do you get?
  27. 27.356? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 53 and take away the sum of its digits. What do you get?
  29. 29.Take 61 and take away the sum of its digits. What do you get?
  30. 30.253? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 11 and take away the sum of its digits. What do you get?
  32. 32.Take 22 and take away the sum of its digits. What do you get?
  33. 33.677? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.52?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 39 and take away the sum of its digits. What do you get?
  36. 36.500? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 81 and take away the sum of its digits. What do you get?
  38. 38.?354 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 76 and take away the sum of its digits. What do you get?
  40. 40.6?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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