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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 391 · 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 4399 ÷ 54? (a) 8800 (b) 880 (c) 88
  2. 2.Best estimate of 3029 ÷ 56? (a) 5000 (b) 50 (c) 500
  3. 3.√92 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  4. 4.√44 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.4 (d) 6.5
  5. 5.√40 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.4
  6. 6.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.3 (d) 5.2
  7. 7.Best estimate of 1885 ÷ 24? (a) 940 (b) 9400 (c) 94
  8. 8.Best estimate of 1321 ÷ 69? (a) 190 (b) 19 (c) 1900
  9. 9.Best estimate of 3141 ÷ 61? (a) 520 (b) 5200 (c) 52
  10. 10.Best estimate of 4420 ÷ 49? (a) 8800 (b) 880 (c) 88
  11. 11.Best estimate of 6986 ÷ 87? (a) 78 (b) 780 (c) 7800
  12. 12.√53 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  13. 13.√59 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.4
  14. 14.Best estimate of 1717 ÷ 39? (a) 430 (b) 43 (c) 4300
  15. 15.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.3 (d) 7.6
  16. 16.√76 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.5 (d) 8.7
  17. 17.Best estimate of 4418 ÷ 48? (a) 8800 (b) 880 (c) 88
  18. 18.Best estimate of 847 ÷ 37? (a) 2100 (b) 21 (c) 210
  19. 19.Best estimate of 3844 ÷ 72? (a) 550 (b) 5500 (c) 55
  20. 20.√22 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 5.0 (d) 4.9
  21. 21.Best estimate of 1862 ÷ 59? (a) 310 (b) 3100 (c) 31
  22. 22.Best estimate of 2673 ÷ 48? (a) 5300 (b) 53 (c) 530
  23. 23.√77 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 9.1 (d) 8.9
  24. 24.√35 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.9 (d) 5.8
  25. 25.Best estimate of 1346 ÷ 78? (a) 1700 (b) 17 (c) 170
  26. 26.√37 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.1 (d) 6.3
  27. 27.Best estimate of 1896 ÷ 82? (a) 24 (b) 240 (c) 2400
  28. 28.Best estimate of 2078 ÷ 51? (a) 4200 (b) 42 (c) 420
  29. 29.Best estimate of 3038 ÷ 46? (a) 6100 (b) 61 (c) 610
  30. 30.Best estimate of 1373 ÷ 53? (a) 270 (b) 27 (c) 2700
  31. 31.Best estimate of 1032 ÷ 38? (a) 260 (b) 26 (c) 2600
  32. 32.Best estimate of 2497 ÷ 81? (a) 3100 (b) 310 (c) 31
  33. 33.√98 to 1 decimal place? (a) 9.8 (b) 10.1 (c) 10.0 (d) 9.9
  34. 34.Best estimate of 454 ÷ 33? (a) 1500 (b) 150 (c) 15
  35. 35.√30 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.8 (d) 5.6
  36. 36.Best estimate of 1724 ÷ 44? (a) 4300 (b) 43 (c) 430
  37. 37.√31 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.3
  38. 38.√75 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 9.0
  39. 39.√34 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.9
  40. 40.Best estimate of 5704 ÷ 68? (a) 810 (b) 8100 (c) 81

Answer key

  1. 88
  2. 50
  3. 9.6
  4. 6.6
  5. 6.3
  6. 5.1
  7. 94
  8. 19
  9. 52
  10. 88
  11. 78
  12. 7.3
  13. 7.7
  14. 43
  15. 7.6
  16. 8.7
  17. 88
  18. 21
  19. 55
  20. 4.7
  21. 31
  22. 53
  23. 8.8
  24. 5.9
  25. 17
  26. 6.1
  27. 24
  28. 42
  29. 61
  30. 27
  31. 26
  32. 31
  33. 9.9
  34. 15
  35. 5.5
  36. 43
  37. 5.6
  38. 8.7
  39. 5.8
  40. 81

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