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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 390 · 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 1860 ÷ 26? (a) 620 (b) 6200 (c) 62
  2. 2.√56 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.7 (d) 7.5
  3. 3.√30 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.4 (d) 5.2
  4. 4.Best estimate of 4491 ÷ 59? (a) 7500 (b) 750 (c) 75
  5. 5.Best estimate of 2558 ÷ 62? (a) 4300 (b) 430 (c) 43
  6. 6.Best estimate of 4532 ÷ 72? (a) 6500 (b) 650 (c) 65
  7. 7.√90 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.6 (d) 9.5
  8. 8.Best estimate of 3703 ÷ 39? (a) 93 (b) 930 (c) 9300
  9. 9.√26 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 4.9 (d) 5.0
  10. 10.Best estimate of 2395 ÷ 82? (a) 300 (b) 3000 (c) 30
  11. 11.Best estimate of 5899 ÷ 74? (a) 840 (b) 84 (c) 8400
  12. 12.√52 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 7.3
  13. 13.Best estimate of 681 ÷ 27? (a) 230 (b) 2300 (c) 23
  14. 14.Best estimate of 7484 ÷ 78? (a) 9400 (b) 940 (c) 94
  15. 15.Best estimate of 5304 ÷ 83? (a) 660 (b) 6600 (c) 66
  16. 16.Best estimate of 4422 ÷ 52? (a) 8800 (b) 880 (c) 88
  17. 17.Best estimate of 7412 ÷ 89? (a) 8200 (b) 820 (c) 82
  18. 18.√55 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.5 (d) 7.4
  19. 19.√78 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 9.0 (d) 8.9
  20. 20.Best estimate of 1450 ÷ 36? (a) 3600 (b) 360 (c) 36
  21. 21.√88 to 1 decimal place? (a) 9.3 (b) 9.6 (c) 9.4 (d) 9.5
  22. 22.√89 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.6
  23. 23.√80 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 8.9 (d) 9.1
  24. 24.√46 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 6.8 (d) 7.0
  25. 25.√87 to 1 decimal place? (a) 9.4 (b) 9.1 (c) 9.3 (d) 9.2
  26. 26.Best estimate of 5913 ÷ 64? (a) 99 (b) 990 (c) 9900
  27. 27.Best estimate of 5764 ÷ 72? (a) 820 (b) 8200 (c) 82
  28. 28.Best estimate of 3970 ÷ 46? (a) 790 (b) 7900 (c) 79
  29. 29.Best estimate of 2919 ÷ 66? (a) 420 (b) 42 (c) 4200
  30. 30.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.8
  31. 31.Best estimate of 3621 ÷ 77? (a) 45 (b) 450 (c) 4500
  32. 32.Best estimate of 1337 ÷ 87? (a) 150 (b) 1500 (c) 15
  33. 33.Best estimate of 5397 ÷ 62? (a) 90 (b) 900 (c) 9000
  34. 34.√40 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.5 (d) 6.4
  35. 35.√28 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.5 (d) 5.3
  36. 36.Best estimate of 940 ÷ 28? (a) 310 (b) 3100 (c) 31
  37. 37.Best estimate of 1473 ÷ 42? (a) 37 (b) 370 (c) 3700
  38. 38.Best estimate of 1168 ÷ 57? (a) 1900 (b) 19 (c) 190
  39. 39.√50 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.1 (d) 7.2
  40. 40.Best estimate of 988 ÷ 26? (a) 33 (b) 330 (c) 3300

Answer key

  1. 62
  2. 7.5
  3. 5.5
  4. 75
  5. 43
  6. 65
  7. 9.5
  8. 93
  9. 5.1
  10. 30
  11. 84
  12. 7.2
  13. 23
  14. 94
  15. 66
  16. 88
  17. 82
  18. 7.4
  19. 8.8
  20. 36
  21. 9.4
  22. 9.4
  23. 8.9
  24. 6.8
  25. 9.3
  26. 99
  27. 82
  28. 79
  29. 42
  30. 9.7
  31. 45
  32. 15
  33. 90
  34. 6.3
  35. 5.3
  36. 31
  37. 37
  38. 19
  39. 7.1
  40. 33

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