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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 224 · 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.?100 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 70 and take away the sum of its digits. What do you get?
  3. 3.37?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?138 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.16?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 99 and take away the sum of its digits. What do you get?
  7. 7.1?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.8?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.4?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 84 and take away the sum of its digits. What do you get?
  11. 11.Take 22 and take away the sum of its digits. What do you get?
  12. 12.?831 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 32 and take away the sum of its digits. What do you get?
  14. 14.Take 67 and take away the sum of its digits. What do you get?
  15. 15.9?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?942 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 78 and take away the sum of its digits. What do you get?
  18. 18.Take 42 and take away the sum of its digits. What do you get?
  19. 19.49?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.1?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 54 and take away the sum of its digits. What do you get?
  22. 22.827? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.7?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?960 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 93 and take away the sum of its digits. What do you get?
  26. 26.Take 44 and take away the sum of its digits. What do you get?
  27. 27.1?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.34?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 13 and take away the sum of its digits. What do you get?
  30. 30.Take 18 and take away the sum of its digits. What do you get?
  31. 31.?732 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.43?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 33 and take away the sum of its digits. What do you get?
  34. 34.47?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 36 and take away the sum of its digits. What do you get?
  37. 37.798? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?438 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?470 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 23 and take away the sum of its digits. What do you get?

Answer key

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

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