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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 130 · 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. 1.1?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 81 and take away the sum of its digits. What do you get?
  3. 3.?669 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?082 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.2?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.4?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.157? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?007 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.212? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.480? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.3?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.5?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?451 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 65 and take away the sum of its digits. What do you get?
  16. 16.Take 60 and take away the sum of its digits. What do you get?
  17. 17.Take 24 and take away the sum of its digits. What do you get?
  18. 18.Take 89 and take away the sum of its digits. What do you get?
  19. 19.Take 46 and take away the sum of its digits. What do you get?
  20. 20.34?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 96 and take away the sum of its digits. What do you get?
  22. 22.63?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 98 and take away the sum of its digits. What do you get?
  24. 24.Take 19 and take away the sum of its digits. What do you get?
  25. 25.?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 61 and take away the sum of its digits. What do you get?
  27. 27.Take 78 and take away the sum of its digits. What do you get?
  28. 28.Take 25 and take away the sum of its digits. What do you get?
  29. 29.?570 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 53 and take away the sum of its digits. What do you get?
  31. 31.Take 64 and take away the sum of its digits. What do you get?
  32. 32.520? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?065 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 23 and take away the sum of its digits. What do you get?
  35. 35.Take 88 and take away the sum of its digits. What do you get?
  36. 36.396? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.63?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?430 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 63 and take away the sum of its digits. What do you get?
  40. 40.?210 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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