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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 233 · 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 43 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.Take 28 and take away the sum of its digits. What do you get?
  4. 4.314? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?053 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.605? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.260? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?385 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 64 and take away the sum of its digits. What do you get?
  10. 10.Take 16 and take away the sum of its digits. What do you get?
  11. 11.74?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.615? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?046 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 96 and take away the sum of its digits. What do you get?
  15. 15.85?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.134? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 56 and take away the sum of its digits. What do you get?
  19. 19.?240 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.213? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?449 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.1?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.896? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.27?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?149 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 73 and take away the sum of its digits. What do you get?
  27. 27.Take 68 and take away the sum of its digits. What do you get?
  28. 28.71? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.4?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 86 and take away the sum of its digits. What do you get?
  31. 31.Take 65 and take away the sum of its digits. What do you get?
  32. 32.40?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 61 and take away the sum of its digits. What do you get?
  34. 34.2?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 98 and take away the sum of its digits. What do you get?
  36. 36.594? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?178 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.65?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.880? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.253? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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