← Digit-sum magic lesson New set →

Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 730 · 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 79 and take away the sum of its digits. What do you get?
  2. 2.Take 81 and take away the sum of its digits. What do you get?
  3. 3.Take 30 and take away the sum of its digits. What do you get?
  4. 4.Take 21 and take away the sum of its digits. What do you get?
  5. 5.567? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.213? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.62? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.6?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.84? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.25?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.71?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.3?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 13 and take away the sum of its digits. What do you get?
  16. 16.?589 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.65?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?077 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.45? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 47 and take away the sum of its digits. What do you get?
  21. 21.Take 95 and take away the sum of its digits. What do you get?
  22. 22.310? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?461 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 28 and take away the sum of its digits. What do you get?
  25. 25.380? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 29 and take away the sum of its digits. What do you get?
  27. 27.458? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.70?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 58 and take away the sum of its digits. What do you get?
  30. 30.Take 66 and take away the sum of its digits. What do you get?
  31. 31.741? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.229? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.26?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?440 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 45 and take away the sum of its digits. What do you get?
  36. 36.Take 70 and take away the sum of its digits. What do you get?
  37. 37.Take 60 and take away the sum of its digits. What do you get?
  38. 38.242? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 25 and take away the sum of its digits. What do you get?
  40. 40.2?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

Free maths tricks lessons, practice and worksheets at talentjr.in/maths-tricks