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Squares Trick Worksheet

Speed calculation lesson 10: Squares next to a ten · Set 899 · 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. 1.79² =
  2. 2.21² =
  3. 3.19² =
  4. 4.71² =
  5. 5.19² =
  6. 6.19² =
  7. 7.79² =
  8. 8.69² =
  9. 9.71² =
  10. 10.69² =
  11. 11.39² =
  12. 12.59² =
  13. 13.39² =
  14. 14.21² =
  15. 15.59² =
  16. 16.41² =
  17. 17.31² =
  18. 18.29² =
  19. 19.29² =
  20. 20.19² =
  21. 21.89² =
  22. 22.59² =
  23. 23.49² =
  24. 24.49² =
  25. 25.91² =
  26. 26.51² =
  27. 27.19² =
  28. 28.51² =
  29. 29.19² =
  30. 30.21² =
  31. 31.51² =
  32. 32.59² =
  33. 33.31² =
  34. 34.39² =
  35. 35.39² =
  36. 36.49² =
  37. 37.59² =
  38. 38.79² =
  39. 39.49² =
  40. 40.21² =

Answer key

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

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