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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 465 · 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.?278 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.2?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 30 and take away the sum of its digits. What do you get?
  4. 4.4?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?059 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.85?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 89 and take away the sum of its digits. What do you get?
  9. 9.59?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.36?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 12 and take away the sum of its digits. What do you get?
  13. 13.Take 32 and take away the sum of its digits. What do you get?
  14. 14.Take 18 and take away the sum of its digits. What do you get?
  15. 15.Take 94 and take away the sum of its digits. What do you get?
  16. 16.5?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 93 and take away the sum of its digits. What do you get?
  18. 18.Take 41 and take away the sum of its digits. What do you get?
  19. 19.Take 70 and take away the sum of its digits. What do you get?
  20. 20.6?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.599? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 26 and take away the sum of its digits. What do you get?
  23. 23.Take 51 and take away the sum of its digits. What do you get?
  24. 24.?691 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 76 and take away the sum of its digits. What do you get?
  26. 26.?615 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.7?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?475 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.1?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 71 and take away the sum of its digits. What do you get?
  31. 31.?210 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?445 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 96 and take away the sum of its digits. What do you get?
  34. 34.393? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.12?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.4?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.5?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.5?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.48?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.7?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 1
  2. 7
  3. 27
  4. 8
  5. 4
  6. 4
  7. 5
  8. 72
  9. 3
  10. 4
  11. 5
  12. 9
  13. 27
  14. 9
  15. 81
  16. 6
  17. 81
  18. 36
  19. 63
  20. 5
  21. 4
  22. 18
  23. 45
  24. 2
  25. 63
  26. 6
  27. 8
  28. 2
  29. 1
  30. 63
  31. 6
  32. 5
  33. 81
  34. 3
  35. 5
  36. 3
  37. 2
  38. 8
  39. 1
  40. 8

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