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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 91 · 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 30 and take away the sum of its digits. What do you get?
  2. 2.3?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?195 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.625? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.758? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.275? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.8?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 37 and take away the sum of its digits. What do you get?
  10. 10.Take 88 and take away the sum of its digits. What do you get?
  11. 11.Take 62 and take away the sum of its digits. What do you get?
  12. 12.?140 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.43?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?456 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?935 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 27 and take away the sum of its digits. What do you get?
  17. 17.?331 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.40? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 52 and take away the sum of its digits. What do you get?
  20. 20.6?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 21 and take away the sum of its digits. What do you get?
  22. 22.Take 29 and take away the sum of its digits. What do you get?
  23. 23.Take 24 and take away the sum of its digits. What do you get?
  24. 24.Take 23 and take away the sum of its digits. What do you get?
  25. 25.Take 80 and take away the sum of its digits. What do you get?
  26. 26.35?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.381? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 68 and take away the sum of its digits. What do you get?
  29. 29.6?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?766 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 15 and take away the sum of its digits. What do you get?
  32. 32.?130 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.11?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.469? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.5?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 55 and take away the sum of its digits. What do you get?
  37. 37.71?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 53 and take away the sum of its digits. What do you get?
  39. 39.35?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.18?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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