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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 187 · 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 7126 ÷ 86? (a) 790 (b) 7900 (c) 79
  2. 2.Best estimate of 444 ÷ 28? (a) 1500 (b) 15 (c) 150
  3. 3.√76 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  4. 4.√38 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.2 (d) 6.1
  5. 5.Best estimate of 3291 ÷ 86? (a) 3700 (b) 370 (c) 37
  6. 6.Best estimate of 2399 ÷ 44? (a) 60 (b) 600 (c) 6000
  7. 7.Best estimate of 4472 ÷ 48? (a) 890 (b) 89 (c) 8900
  8. 8.Best estimate of 2457 ÷ 83? (a) 3100 (b) 310 (c) 31
  9. 9.Best estimate of 2223 ÷ 49? (a) 44 (b) 4400 (c) 440
  10. 10.Best estimate of 1333 ÷ 34? (a) 44 (b) 4400 (c) 440
  11. 11.Best estimate of 505 ÷ 21? (a) 2500 (b) 250 (c) 25
  12. 12.Best estimate of 2860 ÷ 53? (a) 57 (b) 5700 (c) 570
  13. 13.Best estimate of 1198 ÷ 41? (a) 300 (b) 30 (c) 3000
  14. 14.Best estimate of 4116 ÷ 89? (a) 46 (b) 460 (c) 4600
  15. 15.Best estimate of 6212 ÷ 72? (a) 890 (b) 8900 (c) 89
  16. 16.Best estimate of 956 ÷ 56? (a) 16 (b) 160 (c) 1600
  17. 17.Best estimate of 1143 ÷ 52? (a) 23 (b) 230 (c) 2300
  18. 18.Best estimate of 1994 ÷ 33? (a) 66 (b) 660 (c) 6600
  19. 19.√53 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.0 (d) 7.1
  20. 20.√34 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.5 (d) 5.7
  21. 21.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.8 (d) 9.9
  22. 22.Best estimate of 1094 ÷ 41? (a) 27 (b) 270 (c) 2700
  23. 23.Best estimate of 1024 ÷ 49? (a) 20 (b) 2000 (c) 200
  24. 24.Best estimate of 6153 ÷ 73? (a) 88 (b) 880 (c) 8800
  25. 25.Best estimate of 2036 ÷ 62? (a) 340 (b) 3400 (c) 34
  26. 26.Best estimate of 4234 ÷ 54? (a) 850 (b) 8500 (c) 85
  27. 27.√45 to 1 decimal place? (a) 6.6 (b) 6.9 (c) 6.8 (d) 6.7
  28. 28.Best estimate of 3411 ÷ 69? (a) 490 (b) 4900 (c) 49
  29. 29.√61 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  30. 30.√31 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.8 (d) 5.7
  31. 31.Best estimate of 689 ÷ 22? (a) 3400 (b) 34 (c) 340
  32. 32.√69 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.0 (d) 8.1
  33. 33.Best estimate of 553 ÷ 36? (a) 14 (b) 1400 (c) 140
  34. 34.Best estimate of 858 ÷ 32? (a) 29 (b) 290 (c) 2900
  35. 35.√65 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.1
  36. 36.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 4.9 (d) 5.0
  37. 37.Best estimate of 2812 ÷ 62? (a) 47 (b) 4700 (c) 470
  38. 38.√89 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.3
  39. 39.√37 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.2 (d) 6.0
  40. 40.Best estimate of 4839 ÷ 78? (a) 600 (b) 6000 (c) 60

Answer key

  1. 79
  2. 15
  3. 8.7
  4. 6.2
  5. 37
  6. 60
  7. 89
  8. 31
  9. 44
  10. 44
  11. 25
  12. 57
  13. 30
  14. 46
  15. 89
  16. 16
  17. 23
  18. 66
  19. 7.3
  20. 5.8
  21. 9.9
  22. 27
  23. 20
  24. 88
  25. 34
  26. 85
  27. 6.7
  28. 49
  29. 7.8
  30. 5.6
  31. 34
  32. 8.3
  33. 14
  34. 29
  35. 8.1
  36. 5.1
  37. 47
  38. 9.4
  39. 6.1
  40. 60

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