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Squares Trick Worksheet

Speed calculation lesson 10: Squares next to a ten · Set 772 · 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. 2.39² =
  3. 3.19² =
  4. 4.31² =
  5. 5.41² =
  6. 6.39² =
  7. 7.21² =
  8. 8.19² =
  9. 9.89² =
  10. 10.49² =
  11. 11.89² =
  12. 12.69² =
  13. 13.89² =
  14. 14.89² =
  15. 15.79² =
  16. 16.31² =
  17. 17.39² =
  18. 18.89² =
  19. 19.49² =
  20. 20.51² =
  21. 21.91² =
  22. 22.49² =
  23. 23.81² =
  24. 24.81² =
  25. 25.29² =
  26. 26.69² =
  27. 27.59² =
  28. 28.61² =
  29. 29.29² =
  30. 30.81² =
  31. 31.39² =
  32. 32.39² =
  33. 33.69² =
  34. 34.91² =
  35. 35.91² =
  36. 36.71² =
  37. 37.19² =
  38. 38.89² =
  39. 39.79² =
  40. 40.51² =

Answer key

  1. 2401
  2. 1521
  3. 361
  4. 961
  5. 1681
  6. 1521
  7. 441
  8. 361
  9. 7921
  10. 2401
  11. 7921
  12. 4761
  13. 7921
  14. 7921
  15. 6241
  16. 961
  17. 1521
  18. 7921
  19. 2401
  20. 2601
  21. 8281
  22. 2401
  23. 6561
  24. 6561
  25. 841
  26. 4761
  27. 3481
  28. 3721
  29. 841
  30. 6561
  31. 1521
  32. 1521
  33. 4761
  34. 8281
  35. 8281
  36. 5041
  37. 361
  38. 7921
  39. 6241
  40. 2601

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