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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 643 · 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 12 and take away the sum of its digits. What do you get?
  2. 2.?098 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?709 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?579 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?386 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?347 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 30 and take away the sum of its digits. What do you get?
  8. 8.32? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.55? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?692 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 50 and take away the sum of its digits. What do you get?
  12. 12.40?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.241? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 75 and take away the sum of its digits. What do you get?
  15. 15.887? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.30?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 18 and take away the sum of its digits. What do you get?
  18. 18.Take 39 and take away the sum of its digits. What do you get?
  19. 19.Take 88 and take away the sum of its digits. What do you get?
  20. 20.Take 44 and take away the sum of its digits. What do you get?
  21. 21.7?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.25?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.37?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 59 and take away the sum of its digits. What do you get?
  26. 26.Take 87 and take away the sum of its digits. What do you get?
  27. 27.?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.73?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.380? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.885? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.28?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?645 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 79 and take away the sum of its digits. What do you get?
  35. 35.Take 14 and take away the sum of its digits. What do you get?
  36. 36.?967 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?305 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 48 and take away the sum of its digits. What do you get?
  39. 39.169? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?145 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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