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Squares Trick Worksheet

Speed calculation lesson 10: Squares next to a ten · Set 990 · 40 questions
TalentJR

The fast method (Step from a neighbour): Find the round neighbour and square it: 70² = 7 × 7 = 49, then two 0s → 4900. Ends in 1 (one more)? Add the round number and the number: 4900 + 70 + 71. Ends in 9 (one less)? Take them away: 69² = 4900 − 70 − 69 = 4761.

NameDateTime takenScore ___ / 40
  1. 1.29² =
  2. 2.89² =
  3. 3.91² =
  4. 4.81² =
  5. 5.31² =
  6. 6.61² =
  7. 7.79² =
  8. 8.49² =
  9. 9.31² =
  10. 10.61² =
  11. 11.51² =
  12. 12.91² =
  13. 13.41² =
  14. 14.61² =
  15. 15.39² =
  16. 16.41² =
  17. 17.61² =
  18. 18.29² =
  19. 19.59² =
  20. 20.31² =
  21. 21.21² =
  22. 22.49² =
  23. 23.19² =
  24. 24.81² =
  25. 25.41² =
  26. 26.49² =
  27. 27.31² =
  28. 28.41² =
  29. 29.59² =
  30. 30.21² =
  31. 31.39² =
  32. 32.51² =
  33. 33.71² =
  34. 34.49² =
  35. 35.31² =
  36. 36.29² =
  37. 37.39² =
  38. 38.89² =
  39. 39.89² =
  40. 40.71² =

Answer key

  1. 841
  2. 7921
  3. 8281
  4. 6561
  5. 961
  6. 3721
  7. 6241
  8. 2401
  9. 961
  10. 3721
  11. 2601
  12. 8281
  13. 1681
  14. 3721
  15. 1521
  16. 1681
  17. 3721
  18. 841
  19. 3481
  20. 961
  21. 441
  22. 2401
  23. 361
  24. 6561
  25. 1681
  26. 2401
  27. 961
  28. 1681
  29. 3481
  30. 441
  31. 1521
  32. 2601
  33. 5041
  34. 2401
  35. 961
  36. 841
  37. 1521
  38. 7921
  39. 7921
  40. 5041

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