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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 518 · 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.?170 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?366 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?627 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.125? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.65?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 12 and take away the sum of its digits. What do you get?
  7. 7.Take 26 and take away the sum of its digits. What do you get?
  8. 8.?037 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.459? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.76?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.3?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 79 and take away the sum of its digits. What do you get?
  13. 13.4?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?314 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.72?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.5?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.28?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 16 and take away the sum of its digits. What do you get?
  19. 19.8?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 86 and take away the sum of its digits. What do you get?
  21. 21.154? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.6?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 45 and take away the sum of its digits. What do you get?
  25. 25.Take 55 and take away the sum of its digits. What do you get?
  26. 26.4?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?894 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 68 and take away the sum of its digits. What do you get?
  29. 29.2?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 75 and take away the sum of its digits. What do you get?
  31. 31.?787 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 37 and take away the sum of its digits. What do you get?
  33. 33.523? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 25 and take away the sum of its digits. What do you get?
  35. 35.3?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 23 and take away the sum of its digits. What do you get?
  37. 37.6?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 21 and take away the sum of its digits. What do you get?
  39. 39.?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.5?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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