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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 865 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 358 ÷ 27? (a) 12 (b) 1200 (c) 120
  2. 2.√52 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.1 (d) 7.0
  3. 3.Best estimate of 2907 ÷ 42? (a) 7300 (b) 730 (c) 73
  4. 4.Best estimate of 2165 ÷ 33? (a) 7200 (b) 720 (c) 72
  5. 5.Best estimate of 6537 ÷ 89? (a) 73 (b) 7300 (c) 730
  6. 6.Best estimate of 4681 ÷ 81? (a) 590 (b) 59 (c) 5900
  7. 7.Best estimate of 4374 ÷ 84? (a) 5500 (b) 55 (c) 550
  8. 8.√66 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 7.8 (d) 8.0
  9. 9.√65 to 1 decimal place? (a) 8.3 (b) 8.0 (c) 8.1 (d) 8.2
  10. 10.√84 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.1
  11. 11.Best estimate of 472 ÷ 37? (a) 120 (b) 12 (c) 1200
  12. 12.√87 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 9.3
  13. 13.Best estimate of 1753 ÷ 69? (a) 2500 (b) 250 (c) 25
  14. 14.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.9 (d) 5.7
  15. 15.Best estimate of 1999 ÷ 42? (a) 5000 (b) 500 (c) 50
  16. 16.Best estimate of 2619 ÷ 33? (a) 87 (b) 8700 (c) 870
  17. 17.Best estimate of 605 ÷ 37? (a) 150 (b) 15 (c) 1500
  18. 18.√32 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.8 (d) 6.0
  19. 19.Best estimate of 2257 ÷ 87? (a) 2500 (b) 25 (c) 250
  20. 20.Best estimate of 3035 ÷ 87? (a) 340 (b) 3400 (c) 34
  21. 21.Best estimate of 3032 ÷ 58? (a) 510 (b) 5100 (c) 51
  22. 22.Best estimate of 6964 ÷ 88? (a) 770 (b) 7700 (c) 77
  23. 23.√72 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.7
  24. 24.Best estimate of 1609 ÷ 46? (a) 3200 (b) 32 (c) 320
  25. 25.√86 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  26. 26.Best estimate of 4481 ÷ 86? (a) 500 (b) 5000 (c) 50
  27. 27.√92 to 1 decimal place? (a) 9.5 (b) 9.8 (c) 9.6 (d) 9.7
  28. 28.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 10.0
  29. 29.Best estimate of 1782 ÷ 26? (a) 5900 (b) 59 (c) 590
  30. 30.Best estimate of 1997 ÷ 59? (a) 33 (b) 330 (c) 3300
  31. 31.Best estimate of 571 ÷ 36? (a) 14 (b) 1400 (c) 140
  32. 32.Best estimate of 341 ÷ 22? (a) 170 (b) 1700 (c) 17
  33. 33.Best estimate of 2293 ÷ 56? (a) 380 (b) 38 (c) 3800
  34. 34.√26 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 4.9 (d) 5.1
  35. 35.Best estimate of 2603 ÷ 58? (a) 4300 (b) 430 (c) 43
  36. 36.Best estimate of 518 ÷ 32? (a) 1700 (b) 17 (c) 170
  37. 37.Best estimate of 4745 ÷ 83? (a) 590 (b) 5900 (c) 59
  38. 38.Best estimate of 2296 ÷ 52? (a) 46 (b) 460 (c) 4600
  39. 39.√50 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.8 (d) 6.9
  40. 40.Best estimate of 6146 ÷ 72? (a) 88 (b) 8800 (c) 880

Answer key

  1. 12
  2. 7.2
  3. 73
  4. 72
  5. 73
  6. 59
  7. 55
  8. 8.1
  9. 8.1
  10. 9.2
  11. 12
  12. 9.3
  13. 25
  14. 5.8
  15. 50
  16. 87
  17. 15
  18. 5.7
  19. 25
  20. 34
  21. 51
  22. 77
  23. 8.5
  24. 32
  25. 9.3
  26. 50
  27. 9.6
  28. 9.8
  29. 59
  30. 33
  31. 14
  32. 17
  33. 38
  34. 5.1
  35. 43
  36. 17
  37. 59
  38. 46
  39. 7.1
  40. 88

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