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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 186 · 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 83 and take away the sum of its digits. What do you get?
  2. 2.Take 94 and take away the sum of its digits. What do you get?
  3. 3.Take 88 and take away the sum of its digits. What do you get?
  4. 4.85?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.14?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 92 and take away the sum of its digits. What do you get?
  7. 7.8?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?708 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 47 and take away the sum of its digits. What do you get?
  10. 10.Take 25 and take away the sum of its digits. What do you get?
  11. 11.?853 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.6?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 18 and take away the sum of its digits. What do you get?
  15. 15.344? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?583 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?627 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.21?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.78?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.44? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.22?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.537? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.29?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 49 and take away the sum of its digits. What do you get?
  28. 28.Take 98 and take away the sum of its digits. What do you get?
  29. 29.Take 16 and take away the sum of its digits. What do you get?
  30. 30.?637 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 17 and take away the sum of its digits. What do you get?
  32. 32.Take 15 and take away the sum of its digits. What do you get?
  33. 33.?177 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 23 and take away the sum of its digits. What do you get?
  36. 36.12?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?740 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?905 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?712 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 42 and take away the sum of its digits. What do you get?

Answer key

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

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