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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 67 · 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. 1.77? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 98 and take away the sum of its digits. What do you get?
  3. 3.?230 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.8?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.323? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.7?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.8?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.64? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.667? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.60?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.237? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.80?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 39 and take away the sum of its digits. What do you get?
  16. 16.?776 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.1?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 44 and take away the sum of its digits. What do you get?
  19. 19.231? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.30?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?548 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 73 and take away the sum of its digits. What do you get?
  23. 23.2?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 78 and take away the sum of its digits. What do you get?
  25. 25.?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.61?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.603? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 55 and take away the sum of its digits. What do you get?
  29. 29.28?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?511 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 35 and take away the sum of its digits. What do you get?
  32. 32.?506 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.35?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.217? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?276 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 58 and take away the sum of its digits. What do you get?
  37. 37.Take 85 and take away the sum of its digits. What do you get?
  38. 38.12?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 80 and take away the sum of its digits. What do you get?
  40. 40.?195 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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