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Squares Trick Worksheet

Speed calculation lesson 10: Squares next to a ten · Set 679 · 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. 1.21² =
  2. 2.71² =
  3. 3.21² =
  4. 4.19² =
  5. 5.51² =
  6. 6.59² =
  7. 7.89² =
  8. 8.51² =
  9. 9.21² =
  10. 10.31² =
  11. 11.21² =
  12. 12.49² =
  13. 13.59² =
  14. 14.31² =
  15. 15.31² =
  16. 16.91² =
  17. 17.89² =
  18. 18.89² =
  19. 19.91² =
  20. 20.79² =
  21. 21.69² =
  22. 22.31² =
  23. 23.89² =
  24. 24.41² =
  25. 25.69² =
  26. 26.71² =
  27. 27.89² =
  28. 28.61² =
  29. 29.39² =
  30. 30.69² =
  31. 31.49² =
  32. 32.59² =
  33. 33.59² =
  34. 34.71² =
  35. 35.71² =
  36. 36.79² =
  37. 37.21² =
  38. 38.41² =
  39. 39.29² =
  40. 40.61² =

Answer key

  1. 441
  2. 5041
  3. 441
  4. 361
  5. 2601
  6. 3481
  7. 7921
  8. 2601
  9. 441
  10. 961
  11. 441
  12. 2401
  13. 3481
  14. 961
  15. 961
  16. 8281
  17. 7921
  18. 7921
  19. 8281
  20. 6241
  21. 4761
  22. 961
  23. 7921
  24. 1681
  25. 4761
  26. 5041
  27. 7921
  28. 3721
  29. 1521
  30. 4761
  31. 2401
  32. 3481
  33. 3481
  34. 5041
  35. 5041
  36. 6241
  37. 441
  38. 1681
  39. 841
  40. 3721

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