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Squares Trick Worksheet

Speed calculation lesson 10: Squares next to a ten · Set 840 · 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. 1.91² =
  2. 2.21² =
  3. 3.91² =
  4. 4.31² =
  5. 5.51² =
  6. 6.59² =
  7. 7.91² =
  8. 8.91² =
  9. 9.91² =
  10. 10.29² =
  11. 11.61² =
  12. 12.51² =
  13. 13.81² =
  14. 14.39² =
  15. 15.69² =
  16. 16.59² =
  17. 17.29² =
  18. 18.81² =
  19. 19.31² =
  20. 20.49² =
  21. 21.61² =
  22. 22.21² =
  23. 23.89² =
  24. 24.51² =
  25. 25.81² =
  26. 26.59² =
  27. 27.89² =
  28. 28.31² =
  29. 29.91² =
  30. 30.69² =
  31. 31.49² =
  32. 32.61² =
  33. 33.69² =
  34. 34.69² =
  35. 35.71² =
  36. 36.21² =
  37. 37.21² =
  38. 38.29² =
  39. 39.61² =
  40. 40.81² =

Answer key

  1. 8281
  2. 441
  3. 8281
  4. 961
  5. 2601
  6. 3481
  7. 8281
  8. 8281
  9. 8281
  10. 841
  11. 3721
  12. 2601
  13. 6561
  14. 1521
  15. 4761
  16. 3481
  17. 841
  18. 6561
  19. 961
  20. 2401
  21. 3721
  22. 441
  23. 7921
  24. 2601
  25. 6561
  26. 3481
  27. 7921
  28. 961
  29. 8281
  30. 4761
  31. 2401
  32. 3721
  33. 4761
  34. 4761
  35. 5041
  36. 441
  37. 441
  38. 841
  39. 3721
  40. 6561

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