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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 197 · 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 47 and take away the sum of its digits. What do you get?
  2. 2.?156 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.1?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.103? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 70 and take away the sum of its digits. What do you get?
  6. 6.Take 76 and take away the sum of its digits. What do you get?
  7. 7.5?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.23?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?251 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 24 and take away the sum of its digits. What do you get?
  11. 11.6?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.788? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.47?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.69?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?040 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.96? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?703 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.10?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 27 and take away the sum of its digits. What do you get?
  21. 21.Take 85 and take away the sum of its digits. What do you get?
  22. 22.7?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 63 and take away the sum of its digits. What do you get?
  24. 24.2?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 49 and take away the sum of its digits. What do you get?
  26. 26.277? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.12? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?992 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 38 and take away the sum of its digits. What do you get?
  30. 30.Take 80 and take away the sum of its digits. What do you get?
  31. 31.Take 23 and take away the sum of its digits. What do you get?
  32. 32.Take 30 and take away the sum of its digits. What do you get?
  33. 33.Take 93 and take away the sum of its digits. What do you get?
  34. 34.Take 26 and take away the sum of its digits. What do you get?
  35. 35.570? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 39 and take away the sum of its digits. What do you get?
  37. 37.Take 81 and take away the sum of its digits. What do you get?
  38. 38.80? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 75 and take away the sum of its digits. What do you get?
  40. 40.117? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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