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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 389 · 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. 1.3?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?708 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.469? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.77?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.15?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?418 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.4?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.5?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?461 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 34 and take away the sum of its digits. What do you get?
  11. 11.2?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.2?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.772? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 14 and take away the sum of its digits. What do you get?
  15. 15.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 25 and take away the sum of its digits. What do you get?
  17. 17.Take 35 and take away the sum of its digits. What do you get?
  18. 18.Take 69 and take away the sum of its digits. What do you get?
  19. 19.Take 98 and take away the sum of its digits. What do you get?
  20. 20.456? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.5?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.6?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?910 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?551 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?998 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.1?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.227? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.113? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 15 and take away the sum of its digits. What do you get?
  30. 30.Take 43 and take away the sum of its digits. What do you get?
  31. 31.4?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.2?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 17 and take away the sum of its digits. What do you get?
  34. 34.851? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.716? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 78 and take away the sum of its digits. What do you get?
  37. 37.Take 95 and take away the sum of its digits. What do you get?
  38. 38.Take 91 and take away the sum of its digits. What do you get?
  39. 39.616? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.593? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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