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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 220 · 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 26 and take away the sum of its digits. What do you get?
  2. 2.Take 13 and take away the sum of its digits. What do you get?
  3. 3.Take 34 and take away the sum of its digits. What do you get?
  4. 4.14?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.9?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?186 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 18 and take away the sum of its digits. What do you get?
  8. 8.58?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 23 and take away the sum of its digits. What do you get?
  10. 10.6?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?610 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.70?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.549? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 68 and take away the sum of its digits. What do you get?
  15. 15.232? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 91 and take away the sum of its digits. What do you get?
  17. 17.63?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 19 and take away the sum of its digits. What do you get?
  21. 21.Take 56 and take away the sum of its digits. What do you get?
  22. 22.Take 72 and take away the sum of its digits. What do you get?
  23. 23.?439 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?857 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.60?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.386? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 45 and take away the sum of its digits. What do you get?
  28. 28.Take 48 and take away the sum of its digits. What do you get?
  29. 29.375? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.16?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.174? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.67?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 40 and take away the sum of its digits. What do you get?
  34. 34.693? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 36 and take away the sum of its digits. What do you get?
  36. 36.7?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.3?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.440? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.82?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.511? 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. 9
  3. 27
  4. 9
  5. 3
  6. 3
  7. 9
  8. 1
  9. 18
  10. 1
  11. 2
  12. 2
  13. 9
  14. 54
  15. 2
  16. 81
  17. 2
  18. 4
  19. 5
  20. 9
  21. 45
  22. 63
  23. 2
  24. 7
  25. 3
  26. 1
  27. 36
  28. 36
  29. 3
  30. 6
  31. 6
  32. 5
  33. 36
  34. 9
  35. 27
  36. 2
  37. 6
  38. 1
  39. 2
  40. 2

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