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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 45 · 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 56 and take away the sum of its digits. What do you get?
  2. 2.Take 23 and take away the sum of its digits. What do you get?
  3. 3.?462 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?737 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 18 and take away the sum of its digits. What do you get?
  6. 6.?528 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.3?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 42 and take away the sum of its digits. What do you get?
  9. 9.Take 22 and take away the sum of its digits. What do you get?
  10. 10.?043 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.71?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.553? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 98 and take away the sum of its digits. What do you get?
  14. 14.1?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 84 and take away the sum of its digits. What do you get?
  16. 16.15?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 55 and take away the sum of its digits. What do you get?
  18. 18.?077 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 51 and take away the sum of its digits. What do you get?
  20. 20.Take 72 and take away the sum of its digits. What do you get?
  21. 21.?305 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 73 and take away the sum of its digits. What do you get?
  23. 23.?067 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 20 and take away the sum of its digits. What do you get?
  25. 25.?763 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.3?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.270? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.84?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.274? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.606? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.2?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.888? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.268? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 28 and take away the sum of its digits. What do you get?
  36. 36.?458 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.505? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?510 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. 40.444? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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