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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 83 · 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. 1.215? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.41?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?228 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.64? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.407? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.8?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 12 and take away the sum of its digits. What do you get?
  8. 8.2?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 57 and take away the sum of its digits. What do you get?
  10. 10.?651 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.409? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 88 and take away the sum of its digits. What do you get?
  13. 13.Take 67 and take away the sum of its digits. What do you get?
  14. 14.?758 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.97? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 47 and take away the sum of its digits. What do you get?
  17. 17.Take 26 and take away the sum of its digits. What do you get?
  18. 18.2?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?346 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 20 and take away the sum of its digits. What do you get?
  21. 21.Take 16 and take away the sum of its digits. What do you get?
  22. 22.Take 17 and take away the sum of its digits. What do you get?
  23. 23.Take 55 and take away the sum of its digits. What do you get?
  24. 24.Take 75 and take away the sum of its digits. What do you get?
  25. 25.22?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 70 and take away the sum of its digits. What do you get?
  27. 27.Take 37 and take away the sum of its digits. What do you get?
  28. 28.14?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 77 and take away the sum of its digits. What do you get?
  30. 30.Take 49 and take away the sum of its digits. What do you get?
  31. 31.Take 34 and take away the sum of its digits. What do you get?
  32. 32.445? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?955 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.54? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 21 and take away the sum of its digits. What do you get?
  37. 37.42? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.801? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?820 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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