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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 276 · 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.√55 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.5 (d) 7.3
  2. 2.Best estimate of 2345 ÷ 83? (a) 29 (b) 290 (c) 2900
  3. 3.Best estimate of 2654 ÷ 28? (a) 88 (b) 8800 (c) 880
  4. 4.Best estimate of 1072 ÷ 68? (a) 1500 (b) 15 (c) 150
  5. 5.Best estimate of 3992 ÷ 43? (a) 10000 (b) 100 (c) 1000
  6. 6.Best estimate of 967 ÷ 69? (a) 14 (b) 1400 (c) 140
  7. 7.Best estimate of 2303 ÷ 29? (a) 770 (b) 7700 (c) 77
  8. 8.Best estimate of 734 ÷ 31? (a) 2400 (b) 240 (c) 24
  9. 9.√88 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.6 (d) 9.5
  10. 10.Best estimate of 4843 ÷ 62? (a) 8100 (b) 810 (c) 81
  11. 11.√34 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.7 (d) 5.9
  12. 12.Best estimate of 2028 ÷ 67? (a) 290 (b) 29 (c) 2900
  13. 13.Best estimate of 1154 ÷ 38? (a) 2900 (b) 290 (c) 29
  14. 14.Best estimate of 974 ÷ 32? (a) 320 (b) 3200 (c) 32
  15. 15.Best estimate of 3009 ÷ 39? (a) 75 (b) 750 (c) 7500
  16. 16.Best estimate of 3003 ÷ 73? (a) 4300 (b) 43 (c) 430
  17. 17.√50 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.9 (d) 7.2
  18. 18.√48 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.9 (d) 6.7
  19. 19.Best estimate of 3078 ÷ 81? (a) 3800 (b) 38 (c) 380
  20. 20.√61 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 7.8 (d) 7.7
  21. 21.Best estimate of 2284 ÷ 46? (a) 460 (b) 46 (c) 4600
  22. 22.Best estimate of 1206 ÷ 37? (a) 30 (b) 3000 (c) 300
  23. 23.Best estimate of 1957 ÷ 21? (a) 98 (b) 980 (c) 9800
  24. 24.√56 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.5 (d) 7.6
  25. 25.Best estimate of 5275 ÷ 69? (a) 7500 (b) 75 (c) 750
  26. 26.Best estimate of 6118 ÷ 66? (a) 870 (b) 87 (c) 8700
  27. 27.Best estimate of 7149 ÷ 81? (a) 890 (b) 8900 (c) 89
  28. 28.Best estimate of 2261 ÷ 86? (a) 25 (b) 250 (c) 2500
  29. 29.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.2 (d) 4.9
  30. 30.Best estimate of 1150 ÷ 28? (a) 380 (b) 3800 (c) 38
  31. 31.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.3 (d) 5.6
  32. 32.Best estimate of 6887 ÷ 82? (a) 860 (b) 8600 (c) 86
  33. 33.Best estimate of 990 ÷ 48? (a) 2000 (b) 20 (c) 200
  34. 34.√82 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 8.9 (d) 9.1
  35. 35.√38 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 6.3 (d) 6.2
  36. 36.Best estimate of 2593 ÷ 39? (a) 65 (b) 6500 (c) 650
  37. 37.√80 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 8.9 (d) 9.1
  38. 38.√37 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.1 (d) 5.9
  39. 39.√52 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.0 (d) 7.1
  40. 40.Best estimate of 2219 ÷ 82? (a) 2800 (b) 280 (c) 28

Answer key

  1. 7.4
  2. 29
  3. 88
  4. 15
  5. 100
  6. 14
  7. 77
  8. 24
  9. 9.4
  10. 81
  11. 5.8
  12. 29
  13. 29
  14. 32
  15. 75
  16. 43
  17. 7.1
  18. 6.9
  19. 38
  20. 7.8
  21. 46
  22. 30
  23. 98
  24. 7.5
  25. 75
  26. 87
  27. 89
  28. 25
  29. 5.1
  30. 38
  31. 5.5
  32. 86
  33. 20
  34. 9.1
  35. 6.2
  36. 65
  37. 8.9
  38. 6.1
  39. 7.2
  40. 28

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