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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 282 · 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.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.4
  2. 2.√35 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.1 (d) 5.9
  3. 3.Best estimate of 5104 ÷ 88? (a) 570 (b) 5700 (c) 57
  4. 4.√90 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.4
  5. 5.√85 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.1
  6. 6.Best estimate of 5056 ÷ 82? (a) 630 (b) 63 (c) 6300
  7. 7.Best estimate of 5466 ÷ 67? (a) 7800 (b) 78 (c) 780
  8. 8.√46 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 6.8 (d) 7.0
  9. 9.Best estimate of 5249 ÷ 56? (a) 8700 (b) 870 (c) 87
  10. 10.√77 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 9.1 (d) 8.9
  11. 11.√61 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  12. 12.Best estimate of 1583 ÷ 42? (a) 4000 (b) 40 (c) 400
  13. 13.Best estimate of 863 ÷ 36? (a) 22 (b) 2200 (c) 220
  14. 14.Best estimate of 4877 ÷ 63? (a) 8100 (b) 81 (c) 810
  15. 15.√80 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.7 (d) 8.6
  16. 16.√41 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.2
  17. 17.Best estimate of 1664 ÷ 27? (a) 550 (b) 55 (c) 5500
  18. 18.Best estimate of 3069 ÷ 58? (a) 510 (b) 5100 (c) 51
  19. 19.Best estimate of 2551 ÷ 64? (a) 430 (b) 4300 (c) 43
  20. 20.Best estimate of 3521 ÷ 61? (a) 59 (b) 5900 (c) 590
  21. 21.Best estimate of 5573 ÷ 67? (a) 800 (b) 8000 (c) 80
  22. 22.Best estimate of 2270 ÷ 28? (a) 7600 (b) 760 (c) 76
  23. 23.Best estimate of 3796 ÷ 72? (a) 5400 (b) 54 (c) 540
  24. 24.Best estimate of 2737 ÷ 46? (a) 5500 (b) 550 (c) 55
  25. 25.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  26. 26.Best estimate of 4071 ÷ 56? (a) 680 (b) 6800 (c) 68
  27. 27.Best estimate of 5726 ÷ 72? (a) 820 (b) 82 (c) 8200
  28. 28.√75 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.5
  29. 29.√65 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  30. 30.√71 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  31. 31.√28 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.3 (d) 5.1
  32. 32.Best estimate of 3682 ÷ 62? (a) 610 (b) 6100 (c) 61
  33. 33.√40 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.2 (d) 6.3
  34. 34.Best estimate of 525 ÷ 33? (a) 18 (b) 1800 (c) 180
  35. 35.√50 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 7.1
  36. 36.Best estimate of 916 ÷ 42? (a) 230 (b) 23 (c) 2300
  37. 37.√29 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.7 (d) 5.6
  38. 38.Best estimate of 1766 ÷ 46? (a) 35 (b) 350 (c) 3500
  39. 39.Best estimate of 2623 ÷ 74? (a) 370 (b) 3700 (c) 37
  40. 40.Best estimate of 7344 ÷ 82? (a) 9200 (b) 920 (c) 92

Answer key

  1. 7.6
  2. 5.9
  3. 57
  4. 9.5
  5. 9.2
  6. 63
  7. 78
  8. 6.8
  9. 87
  10. 8.8
  11. 7.8
  12. 40
  13. 22
  14. 81
  15. 8.9
  16. 6.4
  17. 55
  18. 51
  19. 43
  20. 59
  21. 80
  22. 76
  23. 54
  24. 55
  25. 5.8
  26. 68
  27. 82
  28. 8.7
  29. 8.1
  30. 8.4
  31. 5.3
  32. 61
  33. 6.3
  34. 18
  35. 7.1
  36. 23
  37. 5.4
  38. 35
  39. 37
  40. 92

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