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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 554 · 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 52 and take away the sum of its digits. What do you get?
  2. 2.?976 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?308 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.8?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 94 and take away the sum of its digits. What do you get?
  6. 6.646? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 83 and take away the sum of its digits. What do you get?
  8. 8.Take 34 and take away the sum of its digits. What do you get?
  9. 9.658? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 67 and take away the sum of its digits. What do you get?
  11. 11.409? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.66?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.2?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.116? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?161 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?415 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 13 and take away the sum of its digits. What do you get?
  18. 18.1?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 89 and take away the sum of its digits. What do you get?
  20. 20.278? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 68 and take away the sum of its digits. What do you get?
  22. 22.?052 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.34?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.126? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?586 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.481? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.7?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.667? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 32 and take away the sum of its digits. What do you get?
  32. 32.?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 95 and take away the sum of its digits. What do you get?
  34. 34.?640 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 25 and take away the sum of its digits. What do you get?
  36. 36.Take 71 and take away the sum of its digits. What do you get?
  37. 37.Take 17 and take away the sum of its digits. What do you get?
  38. 38.410? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?616 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.7?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 45
  2. 5
  3. 7
  4. 4
  5. 81
  6. 2
  7. 72
  8. 27
  9. 8
  10. 54
  11. 5
  12. 6
  13. 9
  14. 1
  15. 1
  16. 8
  17. 9
  18. 5
  19. 72
  20. 1
  21. 54
  22. 2
  23. 2
  24. 9
  25. 6
  26. 8
  27. 5
  28. 9
  29. 1
  30. 8
  31. 27
  32. 1
  33. 81
  34. 8
  35. 18
  36. 63
  37. 9
  38. 4
  39. 5
  40. 5

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