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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 501 · 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 64 and take away the sum of its digits. What do you get?
  2. 2.283? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?820 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?707 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 97 and take away the sum of its digits. What do you get?
  6. 6.?844 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.77?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?914 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.1?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 18 and take away the sum of its digits. What do you get?
  11. 11.55?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.149? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.210? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 51 and take away the sum of its digits. What do you get?
  15. 15.Take 55 and take away the sum of its digits. What do you get?
  16. 16.84?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 19 and take away the sum of its digits. What do you get?
  18. 18.68? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 21 and take away the sum of its digits. What do you get?
  20. 20.Take 22 and take away the sum of its digits. What do you get?
  21. 21.?622 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 67 and take away the sum of its digits. What do you get?
  23. 23.468? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.538? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?418 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.93? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 88 and take away the sum of its digits. What do you get?
  31. 31.Take 41 and take away the sum of its digits. What do you get?
  32. 32.2?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?354 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.4?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.74?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 56 and take away the sum of its digits. What do you get?
  37. 37.Take 44 and take away the sum of its digits. What do you get?
  38. 38.?766 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?665 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?275 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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