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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 891 · 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.√85 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.1
  2. 2.√28 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.1 (d) 5.3
  3. 3.Best estimate of 808 ÷ 58? (a) 130 (b) 1300 (c) 13
  4. 4.Best estimate of 3280 ÷ 39? (a) 8200 (b) 82 (c) 820
  5. 5.√47 to 1 decimal place? (a) 7.1 (b) 6.8 (c) 7.0 (d) 6.9
  6. 6.√29 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.4
  7. 7.Best estimate of 5216 ÷ 78? (a) 65 (b) 6500 (c) 650
  8. 8.√92 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.9
  9. 9.Best estimate of 3802 ÷ 61? (a) 6300 (b) 630 (c) 63
  10. 10.√80 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 9.2
  11. 11.Best estimate of 1335 ÷ 72? (a) 1900 (b) 190 (c) 19
  12. 12.Best estimate of 1666 ÷ 47? (a) 33 (b) 3300 (c) 330
  13. 13.Best estimate of 1260 ÷ 53? (a) 25 (b) 2500 (c) 250
  14. 14.√77 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.7 (d) 8.9
  15. 15.Best estimate of 3483 ÷ 67? (a) 50 (b) 5000 (c) 500
  16. 16.√89 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  17. 17.√45 to 1 decimal place? (a) 6.7 (b) 7.0 (c) 6.9 (d) 6.8
  18. 18.Best estimate of 2954 ÷ 57? (a) 4900 (b) 49 (c) 490
  19. 19.Best estimate of 990 ÷ 23? (a) 5000 (b) 50 (c) 500
  20. 20.Best estimate of 943 ÷ 46? (a) 19 (b) 1900 (c) 190
  21. 21.√74 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.4 (d) 8.5
  22. 22.Best estimate of 1608 ÷ 33? (a) 54 (b) 540 (c) 5400
  23. 23.Best estimate of 5939 ÷ 62? (a) 99 (b) 9900 (c) 990
  24. 24.Best estimate of 1196 ÷ 59? (a) 2000 (b) 200 (c) 20
  25. 25.Best estimate of 757 ÷ 42? (a) 1900 (b) 19 (c) 190
  26. 26.√79 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.1 (d) 9.0
  27. 27.√32 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 5.7
  28. 28.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.1 (d) 10.0
  29. 29.√46 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.9
  30. 30.Best estimate of 1081 ÷ 29? (a) 360 (b) 3600 (c) 36
  31. 31.Best estimate of 3805 ÷ 49? (a) 76 (b) 760 (c) 7600
  32. 32.Best estimate of 4712 ÷ 86? (a) 52 (b) 520 (c) 5200
  33. 33.Best estimate of 2658 ÷ 71? (a) 3800 (b) 380 (c) 38
  34. 34.Best estimate of 573 ÷ 23? (a) 29 (b) 290 (c) 2900
  35. 35.Best estimate of 3036 ÷ 52? (a) 610 (b) 6100 (c) 61
  36. 36.√69 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.5 (d) 8.4
  37. 37.√43 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.5 (d) 6.7
  38. 38.√90 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.6 (d) 9.5
  39. 39.Best estimate of 3478 ÷ 72? (a) 5000 (b) 500 (c) 50
  40. 40.Best estimate of 4252 ÷ 62? (a) 7100 (b) 710 (c) 71

Answer key

  1. 9.2
  2. 5.3
  3. 13
  4. 82
  5. 6.9
  6. 5.4
  7. 65
  8. 9.6
  9. 63
  10. 8.9
  11. 19
  12. 33
  13. 25
  14. 8.8
  15. 50
  16. 9.4
  17. 6.7
  18. 49
  19. 50
  20. 19
  21. 8.6
  22. 54
  23. 99
  24. 20
  25. 19
  26. 8.9
  27. 5.7
  28. 9.8
  29. 6.8
  30. 36
  31. 76
  32. 52
  33. 38
  34. 29
  35. 61
  36. 8.3
  37. 6.6
  38. 9.5
  39. 50
  40. 71

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