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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 397 · 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 25 and take away the sum of its digits. What do you get?
  2. 2.40?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 67 and take away the sum of its digits. What do you get?
  4. 4.56?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?795 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 90 and take away the sum of its digits. What do you get?
  7. 7.24?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 57 and take away the sum of its digits. What do you get?
  9. 9.?607 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 46 and take away the sum of its digits. What do you get?
  11. 11.Take 42 and take away the sum of its digits. What do you get?
  12. 12.Take 62 and take away the sum of its digits. What do you get?
  13. 13.4?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?269 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 88 and take away the sum of its digits. What do you get?
  16. 16.Take 81 and take away the sum of its digits. What do you get?
  17. 17.?901 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.Take 54 and take away the sum of its digits. What do you get?
  20. 20.17?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.191? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?179 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.108? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 48 and take away the sum of its digits. What do you get?
  25. 25.?058 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.35?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?878 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 47 and take away the sum of its digits. What do you get?
  29. 29.Take 44 and take away the sum of its digits. What do you get?
  30. 30.Take 72 and take away the sum of its digits. What do you get?
  31. 31.?691 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.884? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?530 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 14 and take away the sum of its digits. What do you get?
  35. 35.Take 24 and take away the sum of its digits. What do you get?
  36. 36.?317 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 28 and take away the sum of its digits. What do you get?
  38. 38.Take 74 and take away the sum of its digits. What do you get?
  39. 39.Take 40 and take away the sum of its digits. What do you get?
  40. 40.85?0 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. 6
  3. 54
  4. 8
  5. 6
  6. 81
  7. 2
  8. 45
  9. 5
  10. 36
  11. 36
  12. 54
  13. 5
  14. 1
  15. 72
  16. 72
  17. 8
  18. 9
  19. 45
  20. 4
  21. 7
  22. 1
  23. 9
  24. 36
  25. 5
  26. 9
  27. 4
  28. 36
  29. 36
  30. 63
  31. 2
  32. 7
  33. 1
  34. 9
  35. 18
  36. 7
  37. 18
  38. 63
  39. 36
  40. 5

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