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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 23 · 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 98 and take away the sum of its digits. What do you get?
  2. 2.7?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?609 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?722 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.47?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?537 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 25 and take away the sum of its digits. What do you get?
  8. 8.637? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?137 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 70 and take away the sum of its digits. What do you get?
  11. 11.?448 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 64 and take away the sum of its digits. What do you get?
  13. 13.Take 42 and take away the sum of its digits. What do you get?
  14. 14.11?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?316 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 99 and take away the sum of its digits. What do you get?
  17. 17.?110 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 56 and take away the sum of its digits. What do you get?
  19. 19.74?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.4?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.3?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?254 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 84 and take away the sum of its digits. What do you get?
  24. 24.27?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.85?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 14 and take away the sum of its digits. What do you get?
  28. 28.10?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 78 and take away the sum of its digits. What do you get?
  30. 30.?786 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 39 and take away the sum of its digits. What do you get?
  32. 32.308? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?433 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 34 and take away the sum of its digits. What do you get?
  35. 35.?089 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.60? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.84?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.1?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.83?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?863 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 81
  2. 2
  3. 3
  4. 7
  5. 2
  6. 3
  7. 18
  8. 2
  9. 7
  10. 63
  11. 2
  12. 54
  13. 36
  14. 4
  15. 8
  16. 81
  17. 7
  18. 45
  19. 8
  20. 5
  21. 4
  22. 7
  23. 72
  24. 4
  25. 1
  26. 9
  27. 9
  28. 5
  29. 63
  30. 6
  31. 27
  32. 7
  33. 8
  34. 27
  35. 1
  36. 3
  37. 3
  38. 8
  39. 6
  40. 1

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