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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 865 · 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 20 and take away the sum of its digits. What do you get?
  2. 2.?786 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.4?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.4?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 58 and take away the sum of its digits. What do you get?
  6. 6.?935 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.338? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?119 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.4?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.8?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 79 and take away the sum of its digits. What do you get?
  12. 12.Take 70 and take away the sum of its digits. What do you get?
  13. 13.Take 40 and take away the sum of its digits. What do you get?
  14. 14.486? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.5?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 36 and take away the sum of its digits. What do you get?
  17. 17.617? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 86 and take away the sum of its digits. What do you get?
  19. 19.Take 43 and take away the sum of its digits. What do you get?
  20. 20.Take 26 and take away the sum of its digits. What do you get?
  21. 21.Take 57 and take away the sum of its digits. What do you get?
  22. 22.5?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.4?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.10?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.1?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 84 and take away the sum of its digits. What do you get?
  27. 27.Take 96 and take away the sum of its digits. What do you get?
  28. 28.Take 74 and take away the sum of its digits. What do you get?
  29. 29.290? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.8?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 90 and take away the sum of its digits. What do you get?
  32. 32.?272 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 76 and take away the sum of its digits. What do you get?
  34. 34.14?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 14 and take away the sum of its digits. What do you get?
  36. 36.?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.8?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.1?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 16 and take away the sum of its digits. What do you get?
  40. 40.?650 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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