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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 679 · 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 28 and take away the sum of its digits. What do you get?
  2. 2.Take 36 and take away the sum of its digits. What do you get?
  3. 3.?707 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?889 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 56 and take away the sum of its digits. What do you get?
  6. 6.Take 14 and take away the sum of its digits. What do you get?
  7. 7.Take 22 and take away the sum of its digits. What do you get?
  8. 8.6?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 93 and take away the sum of its digits. What do you get?
  10. 10.?759 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.561? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 95 and take away the sum of its digits. What do you get?
  13. 13.Take 34 and take away the sum of its digits. What do you get?
  14. 14.?160 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?951 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 20 and take away the sum of its digits. What do you get?
  18. 18.70?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.22?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 85 and take away the sum of its digits. What do you get?
  21. 21.634? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.123? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.636? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.221? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?481 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.40?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 63 and take away the sum of its digits. What do you get?
  28. 28.3?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.8?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 54 and take away the sum of its digits. What do you get?
  31. 31.761? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.779? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.8?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.1?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.6?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.280? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.67?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 75 and take away the sum of its digits. What do you get?
  39. 39.?233 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.1?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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