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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 358 · 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 72 and take away the sum of its digits. What do you get?
  2. 2.61?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 14 and take away the sum of its digits. What do you get?
  4. 4.Take 31 and take away the sum of its digits. What do you get?
  5. 5.?411 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?388 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 19 and take away the sum of its digits. What do you get?
  8. 8.Take 89 and take away the sum of its digits. What do you get?
  9. 9.?518 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 28 and take away the sum of its digits. What do you get?
  11. 11.624? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?272 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.498? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.39?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.7?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.2?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 81 and take away the sum of its digits. What do you get?
  18. 18.?836 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.60?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?354 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.715? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.899? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 77 and take away the sum of its digits. What do you get?
  24. 24.Take 27 and take away the sum of its digits. What do you get?
  25. 25.16?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 87 and take away the sum of its digits. What do you get?
  27. 27.33?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.19?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.7?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.4?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.1?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 95 and take away the sum of its digits. What do you get?
  33. 33.7?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?469 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.7?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.514? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 45 and take away the sum of its digits. What do you get?
  38. 38.1?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?439 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.145? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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