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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 660 · 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 23 and take away the sum of its digits. What do you get?
  2. 2.?560 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.570? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.2?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.364? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.29?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.311? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 82 and take away the sum of its digits. What do you get?
  9. 9.?464 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 38 and take away the sum of its digits. What do you get?
  11. 11.Take 83 and take away the sum of its digits. What do you get?
  12. 12.573? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?245 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?400 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?786 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.575? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 25 and take away the sum of its digits. What do you get?
  19. 19.127? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?296 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?446 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.8?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.59?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.40? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?104 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 57 and take away the sum of its digits. What do you get?
  27. 27.Take 84 and take away the sum of its digits. What do you get?
  28. 28.Take 33 and take away the sum of its digits. What do you get?
  29. 29.567? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 52 and take away the sum of its digits. What do you get?
  31. 31.Take 60 and take away the sum of its digits. What do you get?
  32. 32.4?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?628 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 44 and take away the sum of its digits. What do you get?
  35. 35.Take 55 and take away the sum of its digits. What do you get?
  36. 36.?431 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.7?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 89 and take away the sum of its digits. What do you get?
  39. 39.3?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 37 and take away the sum of its digits. What do you get?

Answer key

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

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