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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 858 · 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.√67 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.0 (d) 8.3
  2. 2.Best estimate of 4621 ÷ 72? (a) 66 (b) 660 (c) 6600
  3. 3.Best estimate of 3535 ÷ 42? (a) 88 (b) 8800 (c) 880
  4. 4.√26 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 5.1 (d) 4.9
  5. 5.Best estimate of 3694 ÷ 49? (a) 74 (b) 7400 (c) 740
  6. 6.Best estimate of 6003 ÷ 82? (a) 750 (b) 7500 (c) 75
  7. 7.√86 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.0
  8. 8.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.9
  9. 9.Best estimate of 724 ÷ 38? (a) 18 (b) 1800 (c) 180
  10. 10.Best estimate of 1055 ÷ 67? (a) 150 (b) 15 (c) 1500
  11. 11.√78 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.7 (d) 9.0
  12. 12.Best estimate of 4143 ÷ 78? (a) 520 (b) 52 (c) 5200
  13. 13.Best estimate of 2599 ÷ 81? (a) 3200 (b) 320 (c) 32
  14. 14.Best estimate of 5832 ÷ 64? (a) 97 (b) 970 (c) 9700
  15. 15.Best estimate of 512 ÷ 38? (a) 1300 (b) 13 (c) 130
  16. 16.Best estimate of 1719 ÷ 37? (a) 43 (b) 430 (c) 4300
  17. 17.Best estimate of 681 ÷ 21? (a) 340 (b) 34 (c) 3400
  18. 18.Best estimate of 3214 ÷ 89? (a) 360 (b) 36 (c) 3600
  19. 19.Best estimate of 4203 ÷ 58? (a) 700 (b) 7000 (c) 70
  20. 20.Best estimate of 4264 ÷ 49? (a) 8500 (b) 85 (c) 850
  21. 21.Best estimate of 3781 ÷ 59? (a) 6300 (b) 630 (c) 63
  22. 22.√31 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.3
  23. 23.Best estimate of 1473 ÷ 42? (a) 37 (b) 370 (c) 3700
  24. 24.Best estimate of 3383 ÷ 48? (a) 6800 (b) 68 (c) 680
  25. 25.Best estimate of 8092 ÷ 87? (a) 9000 (b) 90 (c) 900
  26. 26.Best estimate of 2276 ÷ 88? (a) 2500 (b) 25 (c) 250
  27. 27.√89 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.6 (d) 9.4
  28. 28.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 6.9 (d) 7.0
  29. 29.√43 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.7 (d) 6.6
  30. 30.√61 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 8.0 (d) 7.8
  31. 31.√52 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.4
  32. 32.Best estimate of 2000 ÷ 26? (a) 6700 (b) 670 (c) 67
  33. 33.Best estimate of 2566 ÷ 32? (a) 860 (b) 86 (c) 8600
  34. 34.√84 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.5
  35. 35.Best estimate of 3967 ÷ 51? (a) 79 (b) 790 (c) 7900
  36. 36.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  37. 37.Best estimate of 1945 ÷ 86? (a) 220 (b) 22 (c) 2200
  38. 38.√77 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.5
  39. 39.Best estimate of 4912 ÷ 88? (a) 550 (b) 55 (c) 5500
  40. 40.Best estimate of 3438 ÷ 36? (a) 86 (b) 8600 (c) 860

Answer key

  1. 8.2
  2. 66
  3. 88
  4. 5.1
  5. 74
  6. 75
  7. 9.3
  8. 9.7
  9. 18
  10. 15
  11. 8.8
  12. 52
  13. 32
  14. 97
  15. 13
  16. 43
  17. 34
  18. 36
  19. 70
  20. 85
  21. 63
  22. 5.6
  23. 37
  24. 68
  25. 90
  26. 25
  27. 9.4
  28. 7.1
  29. 6.6
  30. 7.8
  31. 7.2
  32. 67
  33. 86
  34. 9.2
  35. 79
  36. 8.3
  37. 22
  38. 8.8
  39. 55
  40. 86

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