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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 325 · 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.?118 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.74?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 65 and take away the sum of its digits. What do you get?
  4. 4.Take 98 and take away the sum of its digits. What do you get?
  5. 5.?977 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.351? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 76 and take away the sum of its digits. What do you get?
  8. 8.471? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.48?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 24 and take away the sum of its digits. What do you get?
  11. 11.7?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?876 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?699 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.5?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 15 and take away the sum of its digits. What do you get?
  16. 16.2?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.35?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 48 and take away the sum of its digits. What do you get?
  19. 19.2?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?053 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 87 and take away the sum of its digits. What do you get?
  23. 23.?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.6?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.6?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 46 and take away the sum of its digits. What do you get?
  27. 27.4?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 27 and take away the sum of its digits. What do you get?
  29. 29.?215 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.84?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 45 and take away the sum of its digits. What do you get?
  32. 32.Take 31 and take away the sum of its digits. What do you get?
  33. 33.15?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?937 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.16?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 90 and take away the sum of its digits. What do you get?
  37. 37.51? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 30 and take away the sum of its digits. What do you get?
  39. 39.280? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?498 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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