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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 327 · 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 85 and take away the sum of its digits. What do you get?
  2. 2.80?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.31?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.4?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 17 and take away the sum of its digits. What do you get?
  6. 6.Take 77 and take away the sum of its digits. What do you get?
  7. 7.Take 71 and take away the sum of its digits. What do you get?
  8. 8.?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?177 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?064 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.582? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.35?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.5?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?651 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.835? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.1?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 11 and take away the sum of its digits. What do you get?
  18. 18.Take 24 and take away the sum of its digits. What do you get?
  19. 19.?554 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?939 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.18?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 37 and take away the sum of its digits. What do you get?
  23. 23.41?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?985 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 38 and take away the sum of its digits. What do you get?
  26. 26.1?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.2?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.78?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.67?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?465 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?525 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.37?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 93 and take away the sum of its digits. What do you get?
  34. 34.147? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.5?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 23 and take away the sum of its digits. What do you get?
  37. 37.Take 80 and take away the sum of its digits. What do you get?
  38. 38.?447 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.23?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 27 and take away the sum of its digits. What do you get?

Answer key

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

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