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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 495 · 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.√41 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.4 (d) 6.2
  2. 2.Best estimate of 1681 ÷ 21? (a) 84 (b) 8400 (c) 840
  3. 3.Best estimate of 2208 ÷ 42? (a) 550 (b) 55 (c) 5500
  4. 4.Best estimate of 3630 ÷ 84? (a) 450 (b) 45 (c) 4500
  5. 5.Best estimate of 3366 ÷ 52? (a) 670 (b) 67 (c) 6700
  6. 6.√20 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.4 (d) 4.7
  7. 7.Best estimate of 2096 ÷ 78? (a) 260 (b) 26 (c) 2600
  8. 8.Best estimate of 2018 ÷ 46? (a) 400 (b) 4000 (c) 40
  9. 9.Best estimate of 2875 ÷ 52? (a) 58 (b) 5800 (c) 580
  10. 10.√71 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.5
  11. 11.Best estimate of 3400 ÷ 49? (a) 680 (b) 68 (c) 6800
  12. 12.Best estimate of 2700 ÷ 59? (a) 450 (b) 4500 (c) 45
  13. 13.Best estimate of 1229 ÷ 33? (a) 4100 (b) 410 (c) 41
  14. 14.√26 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 5.0 (d) 4.9
  15. 15.√21 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.9
  16. 16.Best estimate of 2438 ÷ 82? (a) 300 (b) 30 (c) 3000
  17. 17.√65 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.1
  18. 18.√56 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.5 (d) 7.3
  19. 19.Best estimate of 968 ÷ 26? (a) 3200 (b) 320 (c) 32
  20. 20.Best estimate of 552 ÷ 22? (a) 28 (b) 2800 (c) 280
  21. 21.Best estimate of 1372 ÷ 31? (a) 460 (b) 46 (c) 4600
  22. 22.Best estimate of 1039 ÷ 57? (a) 1700 (b) 17 (c) 170
  23. 23.√58 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.6 (d) 7.4
  24. 24.Best estimate of 3095 ÷ 43? (a) 77 (b) 770 (c) 7700
  25. 25.Best estimate of 672 ÷ 54? (a) 1300 (b) 130 (c) 13
  26. 26.Best estimate of 4293 ÷ 64? (a) 72 (b) 720 (c) 7200
  27. 27.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.3 (d) 6.6
  28. 28.√22 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.7 (d) 4.8
  29. 29.√83 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.4 (d) 9.3
  30. 30.Best estimate of 1018 ÷ 46? (a) 200 (b) 2000 (c) 20
  31. 31.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  32. 32.√77 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.9
  33. 33.Best estimate of 7921 ÷ 86? (a) 88 (b) 880 (c) 8800
  34. 34.Best estimate of 1789 ÷ 26? (a) 600 (b) 6000 (c) 60
  35. 35.√88 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.6
  36. 36.√74 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.8 (d) 8.7
  37. 37.Best estimate of 2939 ÷ 38? (a) 730 (b) 73 (c) 7300
  38. 38.Best estimate of 1210 ÷ 61? (a) 200 (b) 20 (c) 2000
  39. 39.√53 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.2
  40. 40.Best estimate of 1453 ÷ 76? (a) 180 (b) 18 (c) 1800

Answer key

  1. 6.4
  2. 84
  3. 55
  4. 45
  5. 67
  6. 4.5
  7. 26
  8. 40
  9. 58
  10. 8.4
  11. 68
  12. 45
  13. 41
  14. 5.1
  15. 4.6
  16. 30
  17. 8.1
  18. 7.5
  19. 32
  20. 28
  21. 46
  22. 17
  23. 7.6
  24. 77
  25. 13
  26. 72
  27. 6.3
  28. 4.7
  29. 9.1
  30. 20
  31. 9.7
  32. 8.8
  33. 88
  34. 60
  35. 9.4
  36. 8.6
  37. 73
  38. 20
  39. 7.3
  40. 18

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