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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 815 · 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 98 and take away the sum of its digits. What do you get?
  2. 2.?112 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.4?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 47 and take away the sum of its digits. What do you get?
  5. 5.3?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 14 and take away the sum of its digits. What do you get?
  7. 7.Take 67 and take away the sum of its digits. What do you get?
  8. 8.Take 24 and take away the sum of its digits. What do you get?
  9. 9.218? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.12?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 74 and take away the sum of its digits. What do you get?
  12. 12.?583 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.597? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.249? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?132 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.263? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.13?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.279? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?830 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 95 and take away the sum of its digits. What do you get?
  21. 21.Take 96 and take away the sum of its digits. What do you get?
  22. 22.Take 87 and take away the sum of its digits. What do you get?
  23. 23.1?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 63 and take away the sum of its digits. What do you get?
  25. 25.?871 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.841? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.500? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.1?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.8?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 53 and take away the sum of its digits. What do you get?
  31. 31.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 48 and take away the sum of its digits. What do you get?
  33. 33.?833 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.6?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.112? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.30?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 25 and take away the sum of its digits. What do you get?
  38. 38.2?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.701? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 81
  2. 5
  3. 5
  4. 36
  5. 6
  6. 9
  7. 54
  8. 18
  9. 7
  10. 7
  11. 63
  12. 2
  13. 6
  14. 3
  15. 3
  16. 7
  17. 1
  18. 9
  19. 7
  20. 81
  21. 81
  22. 72
  23. 9
  24. 54
  25. 2
  26. 5
  27. 4
  28. 4
  29. 5
  30. 45
  31. 2
  32. 36
  33. 4
  34. 6
  35. 5
  36. 9
  37. 18
  38. 4
  39. 9
  40. 1

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