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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 85 · 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. 1.433? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.7?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.51?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.117? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.40?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.54? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 52 and take away the sum of its digits. What do you get?
  8. 8.8?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 70 and take away the sum of its digits. What do you get?
  10. 10.?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 93 and take away the sum of its digits. What do you get?
  12. 12.?197 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.180? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 49 and take away the sum of its digits. What do you get?
  15. 15.Take 80 and take away the sum of its digits. What do you get?
  16. 16.5?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 27 and take away the sum of its digits. What do you get?
  18. 18.Take 47 and take away the sum of its digits. What do you get?
  19. 19.Take 35 and take away the sum of its digits. What do you get?
  20. 20.Take 29 and take away the sum of its digits. What do you get?
  21. 21.?173 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.6?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.737? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.34?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 31 and take away the sum of its digits. What do you get?
  26. 26.68?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?111 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 30 and take away the sum of its digits. What do you get?
  29. 29.Take 20 and take away the sum of its digits. What do you get?
  30. 30.1?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 25 and take away the sum of its digits. What do you get?
  32. 32.Take 57 and take away the sum of its digits. What do you get?
  33. 33.?149 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 21 and take away the sum of its digits. What do you get?
  35. 35.?040 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?278 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.396? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 14 and take away the sum of its digits. What do you get?
  39. 39.1?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.4?48 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. 6
  3. 2
  4. 9
  5. 9
  6. 9
  7. 45
  8. 8
  9. 63
  10. 4
  11. 81
  12. 1
  13. 9
  14. 36
  15. 72
  16. 6
  17. 18
  18. 36
  19. 27
  20. 18
  21. 7
  22. 3
  23. 1
  24. 6
  25. 27
  26. 6
  27. 6
  28. 27
  29. 18
  30. 8
  31. 18
  32. 45
  33. 4
  34. 18
  35. 5
  36. 1
  37. 9
  38. 9
  39. 2
  40. 2

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