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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 366 · 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 56 and take away the sum of its digits. What do you get?
  2. 2.720? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 99 and take away the sum of its digits. What do you get?
  4. 4.?820 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?032 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.834? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.4?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 18 and take away the sum of its digits. What do you get?
  10. 10.Take 25 and take away the sum of its digits. What do you get?
  11. 11.?679 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?166 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?003 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.73?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 94 and take away the sum of its digits. What do you get?
  16. 16.19?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.8?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.831? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.801? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 77 and take away the sum of its digits. What do you get?
  21. 21.68?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.1?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.4?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 60 and take away the sum of its digits. What do you get?
  25. 25.?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.36?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 13 and take away the sum of its digits. What do you get?
  28. 28.?415 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 78 and take away the sum of its digits. What do you get?
  30. 30.?381 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 91 and take away the sum of its digits. What do you get?
  32. 32.?566 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.10? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.7?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 21 and take away the sum of its digits. What do you get?
  36. 36.?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 20 and take away the sum of its digits. What do you get?
  38. 38.4?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.22?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.78?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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