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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 972 · 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 77 and take away the sum of its digits. What do you get?
  2. 2.?176 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.717? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.10?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.452? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.152? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 45 and take away the sum of its digits. What do you get?
  8. 8.79?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 88 and take away the sum of its digits. What do you get?
  10. 10.?520 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 17 and take away the sum of its digits. What do you get?
  13. 13.?548 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 12 and take away the sum of its digits. What do you get?
  15. 15.9?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.51?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.7?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 57 and take away the sum of its digits. What do you get?
  19. 19.3?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.8?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.52? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?181 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.82?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.823? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.21?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.752? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.8?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?952 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 56 and take away the sum of its digits. What do you get?
  30. 30.Take 60 and take away the sum of its digits. What do you get?
  31. 31.55?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 59 and take away the sum of its digits. What do you get?
  33. 33.6?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.558? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 51 and take away the sum of its digits. What do you get?
  36. 36.1?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?433 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.31?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.10?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 36 and take away the sum of its digits. What do you get?

Answer key

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

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