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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 603 · 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 2219 ÷ 44? (a) 5500 (b) 55 (c) 550
  2. 2.Best estimate of 4760 ÷ 52? (a) 9500 (b) 950 (c) 95
  3. 3.√62 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.9 (d) 7.7
  4. 4.√35 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 5.8
  5. 5.√96 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  6. 6.Best estimate of 7353 ÷ 79? (a) 9200 (b) 920 (c) 92
  7. 7.√80 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.0 (d) 9.1
  8. 8.Best estimate of 5160 ÷ 87? (a) 570 (b) 57 (c) 5700
  9. 9.Best estimate of 667 ÷ 26? (a) 2200 (b) 220 (c) 22
  10. 10.√24 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.8 (d) 5.0
  11. 11.Best estimate of 4055 ÷ 59? (a) 68 (b) 680 (c) 6800
  12. 12.√76 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.7 (d) 8.8
  13. 13.Best estimate of 6112 ÷ 66? (a) 87 (b) 870 (c) 8700
  14. 14.Best estimate of 1364 ÷ 27? (a) 450 (b) 45 (c) 4500
  15. 15.√90 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.5 (d) 9.6
  16. 16.Best estimate of 1607 ÷ 83? (a) 200 (b) 20 (c) 2000
  17. 17.√88 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  18. 18.Best estimate of 919 ÷ 47? (a) 18 (b) 180 (c) 1800
  19. 19.Best estimate of 2325 ÷ 69? (a) 330 (b) 33 (c) 3300
  20. 20.Best estimate of 1315 ÷ 56? (a) 220 (b) 22 (c) 2200
  21. 21.Best estimate of 2351 ÷ 62? (a) 3900 (b) 390 (c) 39
  22. 22.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.4 (d) 9.3
  23. 23.√29 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.4 (d) 5.1
  24. 24.√51 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.2 (d) 6.9
  25. 25.Best estimate of 2911 ÷ 44? (a) 730 (b) 7300 (c) 73
  26. 26.Best estimate of 4143 ÷ 44? (a) 1040 (b) 104 (c) 10400
  27. 27.√66 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.1
  28. 28.Best estimate of 5514 ÷ 84? (a) 69 (b) 690 (c) 6900
  29. 29.Best estimate of 582 ÷ 28? (a) 190 (b) 1900 (c) 19
  30. 30.√59 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.6 (d) 7.7
  31. 31.√52 to 1 decimal place? (a) 7.5 (b) 7.2 (c) 7.4 (d) 7.3
  32. 32.Best estimate of 5628 ÷ 67? (a) 800 (b) 8000 (c) 80
  33. 33.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.5
  34. 34.Best estimate of 2562 ÷ 42? (a) 6400 (b) 64 (c) 640
  35. 35.Best estimate of 589 ÷ 23? (a) 2900 (b) 29 (c) 290
  36. 36.√72 to 1 decimal place? (a) 8.5 (b) 8.8 (c) 8.6 (d) 8.7
  37. 37.Best estimate of 5466 ÷ 62? (a) 91 (b) 9100 (c) 910
  38. 38.√92 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.8 (d) 9.6
  39. 39.√58 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.3 (d) 7.6
  40. 40.Best estimate of 2809 ÷ 76? (a) 35 (b) 350 (c) 3500

Answer key

  1. 55
  2. 95
  3. 7.9
  4. 5.9
  5. 9.8
  6. 92
  7. 8.9
  8. 57
  9. 22
  10. 4.9
  11. 68
  12. 8.7
  13. 87
  14. 45
  15. 9.5
  16. 20
  17. 9.4
  18. 18
  19. 33
  20. 22
  21. 39
  22. 9.1
  23. 5.4
  24. 7.1
  25. 73
  26. 104
  27. 8.1
  28. 69
  29. 19
  30. 7.7
  31. 7.2
  32. 80
  33. 6.6
  34. 64
  35. 29
  36. 8.5
  37. 91
  38. 9.6
  39. 7.6
  40. 35

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