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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 43 · 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 4233 ÷ 89? (a) 47 (b) 470 (c) 4700
  2. 2.Best estimate of 2572 ÷ 66? (a) 37 (b) 370 (c) 3700
  3. 3.Best estimate of 2892 ÷ 39? (a) 72 (b) 7200 (c) 720
  4. 4.√85 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 8.9 (d) 9.0
  5. 5.Best estimate of 791 ÷ 44? (a) 200 (b) 2000 (c) 20
  6. 6.Best estimate of 1299 ÷ 54? (a) 26 (b) 2600 (c) 260
  7. 7.Best estimate of 2463 ÷ 26? (a) 820 (b) 82 (c) 8200
  8. 8.Best estimate of 3418 ÷ 52? (a) 68 (b) 680 (c) 6800
  9. 9.√96 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.7 (d) 9.9
  10. 10.Best estimate of 3521 ÷ 54? (a) 700 (b) 7000 (c) 70
  11. 11.√51 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.4
  12. 12.√48 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 7.1 (d) 6.8
  13. 13.√41 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.1
  14. 14.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.4 (d) 4.3
  15. 15.√79 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  16. 16.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.1 (d) 6.2
  17. 17.Best estimate of 1080 ÷ 82? (a) 14 (b) 140 (c) 1400
  18. 18.√26 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.2 (d) 5.1
  19. 19.Best estimate of 1182 ÷ 22? (a) 59 (b) 5900 (c) 590
  20. 20.Best estimate of 2090 ÷ 23? (a) 105 (b) 10500 (c) 1050
  21. 21.√70 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.6 (d) 8.5
  22. 22.Best estimate of 831 ÷ 62? (a) 14 (b) 1400 (c) 140
  23. 23.√86 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.6
  24. 24.Best estimate of 1152 ÷ 53? (a) 2300 (b) 23 (c) 230
  25. 25.√22 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 5.0 (d) 4.9
  26. 26.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.7
  27. 27.Best estimate of 1693 ÷ 67? (a) 24 (b) 2400 (c) 240
  28. 28.Best estimate of 2594 ÷ 82? (a) 3200 (b) 320 (c) 32
  29. 29.√98 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.8 (d) 9.9
  30. 30.Best estimate of 1194 ÷ 33? (a) 400 (b) 40 (c) 4000
  31. 31.√52 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.3 (d) 7.1
  32. 32.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.7 (d) 5.8
  33. 33.Best estimate of 479 ÷ 26? (a) 16 (b) 1600 (c) 160
  34. 34.Best estimate of 4626 ÷ 62? (a) 770 (b) 7700 (c) 77
  35. 35.Best estimate of 1626 ÷ 58? (a) 27 (b) 270 (c) 2700
  36. 36.Best estimate of 444 ÷ 27? (a) 15 (b) 150 (c) 1500
  37. 37.Best estimate of 5530 ÷ 82? (a) 6900 (b) 69 (c) 690
  38. 38.Best estimate of 813 ÷ 54? (a) 16 (b) 1600 (c) 160
  39. 39.Best estimate of 1032 ÷ 23? (a) 5200 (b) 520 (c) 52
  40. 40.Best estimate of 1583 ÷ 44? (a) 4000 (b) 400 (c) 40

Answer key

  1. 47
  2. 37
  3. 72
  4. 9.2
  5. 20
  6. 26
  7. 82
  8. 68
  9. 9.8
  10. 70
  11. 7.1
  12. 6.9
  13. 6.4
  14. 4.5
  15. 8.9
  16. 6.3
  17. 14
  18. 5.1
  19. 59
  20. 105
  21. 8.4
  22. 14
  23. 9.3
  24. 23
  25. 4.7
  26. 7.4
  27. 24
  28. 32
  29. 9.9
  30. 40
  31. 7.2
  32. 5.8
  33. 16
  34. 77
  35. 27
  36. 15
  37. 69
  38. 16
  39. 52
  40. 40

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