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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 491 · 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.√66 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  2. 2.Best estimate of 1725 ÷ 49? (a) 350 (b) 3500 (c) 35
  3. 3.√52 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.2 (d) 7.0
  4. 4.Best estimate of 2529 ÷ 31? (a) 84 (b) 8400 (c) 840
  5. 5.Best estimate of 7582 ÷ 82? (a) 950 (b) 95 (c) 9500
  6. 6.√28 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.3 (d) 5.5
  7. 7.Best estimate of 7710 ÷ 82? (a) 96 (b) 960 (c) 9600
  8. 8.√37 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 5.8 (d) 5.9
  9. 9.Best estimate of 1689 ÷ 41? (a) 420 (b) 4200 (c) 42
  10. 10.√23 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.5
  11. 11.Best estimate of 2596 ÷ 39? (a) 6500 (b) 65 (c) 650
  12. 12.√65 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.9 (d) 8.1
  13. 13.Best estimate of 4411 ÷ 71? (a) 63 (b) 630 (c) 6300
  14. 14.Best estimate of 4938 ÷ 86? (a) 5500 (b) 550 (c) 55
  15. 15.Best estimate of 920 ÷ 39? (a) 230 (b) 2300 (c) 23
  16. 16.√22 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.7 (d) 4.9
  17. 17.Best estimate of 1444 ÷ 34? (a) 4800 (b) 48 (c) 480
  18. 18.√34 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.8 (d) 5.6
  19. 19.Best estimate of 7508 ÷ 89? (a) 8300 (b) 83 (c) 830
  20. 20.√98 to 1 decimal place? (a) 9.7 (b) 10.0 (c) 9.8 (d) 9.9
  21. 21.Best estimate of 3731 ÷ 61? (a) 6200 (b) 620 (c) 62
  22. 22.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.2 (d) 6.3
  23. 23.Best estimate of 3237 ÷ 62? (a) 540 (b) 5400 (c) 54
  24. 24.Best estimate of 2436 ÷ 72? (a) 3500 (b) 35 (c) 350
  25. 25.√26 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.0 (d) 5.2
  26. 26.√83 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 9.2
  27. 27.Best estimate of 1507 ÷ 58? (a) 250 (b) 25 (c) 2500
  28. 28.Best estimate of 1584 ÷ 26? (a) 53 (b) 530 (c) 5300
  29. 29.√24 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 4.8
  30. 30.Best estimate of 1583 ÷ 28? (a) 5300 (b) 530 (c) 53
  31. 31.Best estimate of 1129 ÷ 27? (a) 380 (b) 38 (c) 3800
  32. 32.√45 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.8
  33. 33.√56 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.4 (d) 7.3
  34. 34.Best estimate of 1382 ÷ 76? (a) 17 (b) 1700 (c) 170
  35. 35.Best estimate of 1206 ÷ 39? (a) 300 (b) 3000 (c) 30
  36. 36.√76 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.7
  37. 37.Best estimate of 7084 ÷ 81? (a) 890 (b) 8900 (c) 89
  38. 38.Best estimate of 4123 ÷ 76? (a) 520 (b) 5200 (c) 52
  39. 39.Best estimate of 6518 ÷ 86? (a) 720 (b) 72 (c) 7200
  40. 40.Best estimate of 535 ÷ 38? (a) 1300 (b) 130 (c) 13

Answer key

  1. 8.1
  2. 35
  3. 7.2
  4. 84
  5. 95
  6. 5.3
  7. 96
  8. 6.1
  9. 42
  10. 4.8
  11. 65
  12. 8.1
  13. 63
  14. 55
  15. 23
  16. 4.7
  17. 48
  18. 5.8
  19. 83
  20. 9.9
  21. 62
  22. 6.3
  23. 54
  24. 35
  25. 5.1
  26. 9.1
  27. 25
  28. 53
  29. 4.9
  30. 53
  31. 38
  32. 6.7
  33. 7.5
  34. 17
  35. 30
  36. 8.7
  37. 89
  38. 52
  39. 72
  40. 13

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