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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 592 · 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. 1.73?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.593? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 87 and take away the sum of its digits. What do you get?
  4. 4.?138 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 86 and take away the sum of its digits. What do you get?
  6. 6.417? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.1?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?174 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.680? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.418? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.82? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?565 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 67 and take away the sum of its digits. What do you get?
  14. 14.614? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 53 and take away the sum of its digits. What do you get?
  16. 16.14?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 40 and take away the sum of its digits. What do you get?
  18. 18.604? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.7?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.285? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.51? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 29 and take away the sum of its digits. What do you get?
  23. 23.Take 74 and take away the sum of its digits. What do you get?
  24. 24.?150 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 28 and take away the sum of its digits. What do you get?
  26. 26.1?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?605 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.76?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?346 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?502 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 94 and take away the sum of its digits. What do you get?
  32. 32.Take 92 and take away the sum of its digits. What do you get?
  33. 33.Take 69 and take away the sum of its digits. What do you get?
  34. 34.Take 42 and take away the sum of its digits. What do you get?
  35. 35.Take 36 and take away the sum of its digits. What do you get?
  36. 36.Take 35 and take away the sum of its digits. What do you get?
  37. 37.Take 54 and take away the sum of its digits. What do you get?
  38. 38.?064 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.879? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?933 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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