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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 354 · 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 41 and take away the sum of its digits. What do you get?
  2. 2.?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.389? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 86 and take away the sum of its digits. What do you get?
  5. 5.Take 14 and take away the sum of its digits. What do you get?
  6. 6.?400 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.7?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?328 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.3?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 93 and take away the sum of its digits. What do you get?
  11. 11.612? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 65 and take away the sum of its digits. What do you get?
  14. 14.Take 69 and take away the sum of its digits. What do you get?
  15. 15.Take 23 and take away the sum of its digits. What do you get?
  16. 16.?451 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 84 and take away the sum of its digits. What do you get?
  18. 18.208? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 82 and take away the sum of its digits. What do you get?
  20. 20.64?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.1?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.40?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.7?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?748 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 62 and take away the sum of its digits. What do you get?
  27. 27.Take 99 and take away the sum of its digits. What do you get?
  28. 28.Take 95 and take away the sum of its digits. What do you get?
  29. 29.3?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?150 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.745? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 37 and take away the sum of its digits. What do you get?
  33. 33.580? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.5?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 11 and take away the sum of its digits. What do you get?
  36. 36.15?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 45 and take away the sum of its digits. What do you get?
  38. 38.Take 98 and take away the sum of its digits. What do you get?
  39. 39.23?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?149 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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