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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 814 · 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 80 and take away the sum of its digits. What do you get?
  2. 2.8?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 66 and take away the sum of its digits. What do you get?
  4. 4.816? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.54? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 94 and take away the sum of its digits. What do you get?
  7. 7.Take 38 and take away the sum of its digits. What do you get?
  8. 8.2?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 50 and take away the sum of its digits. What do you get?
  10. 10.?395 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 78 and take away the sum of its digits. What do you get?
  12. 12.?269 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?556 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.384? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.3?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.47? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?329 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.23?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.42?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.8?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.332? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 72 and take away the sum of its digits. What do you get?
  23. 23.Take 13 and take away the sum of its digits. What do you get?
  24. 24.Take 76 and take away the sum of its digits. What do you get?
  25. 25.34?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?502 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.13?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?546 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 27 and take away the sum of its digits. What do you get?
  30. 30.Take 22 and take away the sum of its digits. What do you get?
  31. 31.18?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.557? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.37? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 61 and take away the sum of its digits. What do you get?
  35. 35.Take 90 and take away the sum of its digits. What do you get?
  36. 36.Take 92 and take away the sum of its digits. What do you get?
  37. 37.?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.18?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 69 and take away the sum of its digits. What do you get?
  40. 40.?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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