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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 346 · 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 98 and take away the sum of its digits. What do you get?
  2. 2.Take 88 and take away the sum of its digits. What do you get?
  3. 3.Take 35 and take away the sum of its digits. What do you get?
  4. 4.?062 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 22 and take away the sum of its digits. What do you get?
  6. 6.?456 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?320 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.518? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 46 and take away the sum of its digits. What do you get?
  10. 10.Take 62 and take away the sum of its digits. What do you get?
  11. 11.Take 71 and take away the sum of its digits. What do you get?
  12. 12.7?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.555? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.4?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.10?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 15 and take away the sum of its digits. What do you get?
  17. 17.?127 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?717 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.598? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?930 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.236? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 64 and take away the sum of its digits. What do you get?
  26. 26.?530 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 91 and take away the sum of its digits. What do you get?
  28. 28.Take 32 and take away the sum of its digits. What do you get?
  29. 29.?548 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.386? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.39?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?260 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 28 and take away the sum of its digits. What do you get?
  34. 34.178? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.8?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.8?60 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.?956 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.67?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.6?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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