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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 624 · 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.?010 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.330? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.687? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 89 and take away the sum of its digits. What do you get?
  5. 5.?293 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 49 and take away the sum of its digits. What do you get?
  7. 7.3?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?520 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 16 and take away the sum of its digits. What do you get?
  11. 11.Take 98 and take away the sum of its digits. What do you get?
  12. 12.4?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?064 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.33? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.430? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 61 and take away the sum of its digits. What do you get?
  17. 17.Take 48 and take away the sum of its digits. What do you get?
  18. 18.89?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.78?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 40 and take away the sum of its digits. What do you get?
  21. 21.Take 65 and take away the sum of its digits. What do you get?
  22. 22.Take 68 and take away the sum of its digits. What do you get?
  23. 23.Take 30 and take away the sum of its digits. What do you get?
  24. 24.8?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.70?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 23 and take away the sum of its digits. What do you get?
  28. 28.5?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.85? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.8?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.556? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 72 and take away the sum of its digits. What do you get?
  34. 34.?093 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 13 and take away the sum of its digits. What do you get?
  36. 36.2?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.5?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.89? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.719? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.40?4 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. 3
  3. 6
  4. 72
  5. 4
  6. 36
  7. 1
  8. 2
  9. 5
  10. 9
  11. 81
  12. 1
  13. 8
  14. 3
  15. 2
  16. 54
  17. 36
  18. 4
  19. 6
  20. 36
  21. 54
  22. 54
  23. 27
  24. 3
  25. 2
  26. 8
  27. 18
  28. 4
  29. 5
  30. 5
  31. 6
  32. 2
  33. 63
  34. 6
  35. 9
  36. 4
  37. 8
  38. 1
  39. 1
  40. 1

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