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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 494 · 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. 1.75?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.202? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 36 and take away the sum of its digits. What do you get?
  4. 4.?347 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.29?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.57?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.63?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?796 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?313 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.326? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 51 and take away the sum of its digits. What do you get?
  13. 13.Take 59 and take away the sum of its digits. What do you get?
  14. 14.Take 62 and take away the sum of its digits. What do you get?
  15. 15.1?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.29?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.720? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.24?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 14 and take away the sum of its digits. What do you get?
  21. 21.Take 98 and take away the sum of its digits. What do you get?
  22. 22.?409 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 13 and take away the sum of its digits. What do you get?
  24. 24.Take 39 and take away the sum of its digits. What do you get?
  25. 25.?616 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?480 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.76?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.449? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?139 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.14?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.4?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 66 and take away the sum of its digits. What do you get?
  34. 34.3?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.5?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.380? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.2?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 79 and take away the sum of its digits. What do you get?
  39. 39.?561 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 80 and take away the sum of its digits. What do you get?

Answer key

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

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