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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 668 · 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 1160 ÷ 21? (a) 580 (b) 58 (c) 5800
  2. 2.√61 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.7 (d) 7.5
  3. 3.Best estimate of 3826 ÷ 72? (a) 5500 (b) 550 (c) 55
  4. 4.√96 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.8 (d) 9.6
  5. 5.√88 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.5
  6. 6.Best estimate of 4232 ÷ 52? (a) 85 (b) 8500 (c) 850
  7. 7.Best estimate of 1024 ÷ 26? (a) 3400 (b) 340 (c) 34
  8. 8.Best estimate of 4536 ÷ 83? (a) 5700 (b) 570 (c) 57
  9. 9.Best estimate of 4037 ÷ 56? (a) 6700 (b) 67 (c) 670
  10. 10.Best estimate of 2138 ÷ 42? (a) 530 (b) 5300 (c) 53
  11. 11.√76 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.7 (d) 9.0
  12. 12.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.7
  13. 13.√87 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.5
  14. 14.√41 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.5
  15. 15.√24 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 5.1 (d) 4.9
  16. 16.Best estimate of 1599 ÷ 72? (a) 23 (b) 230 (c) 2300
  17. 17.Best estimate of 2637 ÷ 46? (a) 53 (b) 530 (c) 5300
  18. 18.Best estimate of 3728 ÷ 76? (a) 470 (b) 47 (c) 4700
  19. 19.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 5.9 (d) 6.0
  20. 20.Best estimate of 3813 ÷ 69? (a) 540 (b) 5400 (c) 54
  21. 21.Best estimate of 627 ÷ 36? (a) 160 (b) 1600 (c) 16
  22. 22.Best estimate of 1196 ÷ 38? (a) 300 (b) 3000 (c) 30
  23. 23.Best estimate of 3390 ÷ 77? (a) 4200 (b) 42 (c) 420
  24. 24.√66 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.3 (d) 8.0
  25. 25.Best estimate of 1220 ÷ 81? (a) 150 (b) 1500 (c) 15
  26. 26.√71 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.2
  27. 27.Best estimate of 1763 ÷ 38? (a) 440 (b) 44 (c) 4400
  28. 28.√89 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.7
  29. 29.√46 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 7.1 (d) 7.0
  30. 30.Best estimate of 5216 ÷ 68? (a) 75 (b) 7500 (c) 750
  31. 31.√40 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 6.3
  32. 32.Best estimate of 2094 ÷ 33? (a) 700 (b) 7000 (c) 70
  33. 33.Best estimate of 3964 ÷ 83? (a) 500 (b) 5000 (c) 50
  34. 34.√74 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.3
  35. 35.√75 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  36. 36.√69 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.2
  37. 37.Best estimate of 3980 ÷ 88? (a) 440 (b) 44 (c) 4400
  38. 38.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.9
  39. 39.Best estimate of 5929 ÷ 77? (a) 74 (b) 740 (c) 7400
  40. 40.Best estimate of 1488 ÷ 29? (a) 5000 (b) 500 (c) 50

Answer key

  1. 58
  2. 7.8
  3. 55
  4. 9.8
  5. 9.4
  6. 85
  7. 34
  8. 57
  9. 67
  10. 53
  11. 8.7
  12. 7.4
  13. 9.3
  14. 6.4
  15. 4.9
  16. 23
  17. 53
  18. 47
  19. 6.1
  20. 54
  21. 16
  22. 30
  23. 42
  24. 8.1
  25. 15
  26. 8.4
  27. 44
  28. 9.4
  29. 6.8
  30. 75
  31. 6.3
  32. 70
  33. 50
  34. 8.6
  35. 8.7
  36. 8.3
  37. 44
  38. 5.8
  39. 74
  40. 50

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