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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 249 · 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 54 and take away the sum of its digits. What do you get?
  2. 2.Take 21 and take away the sum of its digits. What do you get?
  3. 3.?028 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?393 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 25 and take away the sum of its digits. What do you get?
  6. 6.1?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 45 and take away the sum of its digits. What do you get?
  8. 8.Take 29 and take away the sum of its digits. What do you get?
  9. 9.Take 27 and take away the sum of its digits. What do you get?
  10. 10.80?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?730 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 30 and take away the sum of its digits. What do you get?
  13. 13.115? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 76 and take away the sum of its digits. What do you get?
  15. 15.51?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.586? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 71 and take away the sum of its digits. What do you get?
  18. 18.Take 16 and take away the sum of its digits. What do you get?
  19. 19.8?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.38?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.5?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.24?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?143 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.868? 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. 26.18?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.76?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 15 and take away the sum of its digits. What do you get?
  29. 29.?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 41 and take away the sum of its digits. What do you get?
  31. 31.41?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 77 and take away the sum of its digits. What do you get?
  33. 33.49?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?647 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?259 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.35?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.13?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.1?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.9?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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