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Squares Trick Worksheet

Speed calculation lesson 10: Squares next to a ten · Set 921 · 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. 1.49² =
  2. 2.59² =
  3. 3.39² =
  4. 4.21² =
  5. 5.69² =
  6. 6.69² =
  7. 7.61² =
  8. 8.21² =
  9. 9.49² =
  10. 10.19² =
  11. 11.49² =
  12. 12.21² =
  13. 13.19² =
  14. 14.69² =
  15. 15.69² =
  16. 16.19² =
  17. 17.59² =
  18. 18.81² =
  19. 19.69² =
  20. 20.79² =
  21. 21.21² =
  22. 22.81² =
  23. 23.19² =
  24. 24.29² =
  25. 25.41² =
  26. 26.39² =
  27. 27.51² =
  28. 28.31² =
  29. 29.49² =
  30. 30.21² =
  31. 31.81² =
  32. 32.61² =
  33. 33.31² =
  34. 34.41² =
  35. 35.49² =
  36. 36.69² =
  37. 37.89² =
  38. 38.59² =
  39. 39.89² =
  40. 40.59² =

Answer key

  1. 2401
  2. 3481
  3. 1521
  4. 441
  5. 4761
  6. 4761
  7. 3721
  8. 441
  9. 2401
  10. 361
  11. 2401
  12. 441
  13. 361
  14. 4761
  15. 4761
  16. 361
  17. 3481
  18. 6561
  19. 4761
  20. 6241
  21. 441
  22. 6561
  23. 361
  24. 841
  25. 1681
  26. 1521
  27. 2601
  28. 961
  29. 2401
  30. 441
  31. 6561
  32. 3721
  33. 961
  34. 1681
  35. 2401
  36. 4761
  37. 7921
  38. 3481
  39. 7921
  40. 3481

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