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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 871 · 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 3571 ÷ 79? (a) 450 (b) 4500 (c) 45
  2. 2.√35 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.7 (d) 5.8
  3. 3.√92 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.7 (d) 9.5
  4. 4.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.4
  5. 5.Best estimate of 1073 ÷ 36? (a) 27 (b) 2700 (c) 270
  6. 6.Best estimate of 974 ÷ 38? (a) 24 (b) 240 (c) 2400
  7. 7.Best estimate of 6135 ÷ 83? (a) 770 (b) 7700 (c) 77
  8. 8.Best estimate of 2605 ÷ 71? (a) 370 (b) 3700 (c) 37
  9. 9.√51 to 1 decimal place? (a) 6.8 (b) 7.1 (c) 7.0 (d) 6.9
  10. 10.√87 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.1 (d) 9.2
  11. 11.Best estimate of 452 ÷ 23? (a) 230 (b) 2300 (c) 23
  12. 12.Best estimate of 1778 ÷ 33? (a) 590 (b) 5900 (c) 59
  13. 13.√58 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.5 (d) 7.3
  14. 14.√48 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 7.0 (d) 6.7
  15. 15.Best estimate of 2000 ÷ 26? (a) 6700 (b) 67 (c) 670
  16. 16.Best estimate of 6206 ÷ 76? (a) 78 (b) 780 (c) 7800
  17. 17.Best estimate of 1849 ÷ 26? (a) 6200 (b) 620 (c) 62
  18. 18.√24 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 4.9 (d) 5.0
  19. 19.√89 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.6
  20. 20.Best estimate of 7881 ÷ 89? (a) 8800 (b) 88 (c) 880
  21. 21.Best estimate of 2855 ÷ 79? (a) 360 (b) 36 (c) 3600
  22. 22.√43 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.6
  23. 23.Best estimate of 2419 ÷ 58? (a) 4000 (b) 40 (c) 400
  24. 24.Best estimate of 1780 ÷ 36? (a) 4500 (b) 450 (c) 45
  25. 25.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.1
  26. 26.Best estimate of 4258 ÷ 86? (a) 4700 (b) 470 (c) 47
  27. 27.Best estimate of 1441 ÷ 56? (a) 240 (b) 24 (c) 2400
  28. 28.√23 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.5 (d) 4.7
  29. 29.Best estimate of 1133 ÷ 66? (a) 1600 (b) 16 (c) 160
  30. 30.Best estimate of 2247 ÷ 52? (a) 45 (b) 450 (c) 4500
  31. 31.Best estimate of 1048 ÷ 46? (a) 2100 (b) 21 (c) 210
  32. 32.√32 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.5 (d) 5.7
  33. 33.Best estimate of 1250 ÷ 31? (a) 420 (b) 4200 (c) 42
  34. 34.Best estimate of 3001 ÷ 67? (a) 430 (b) 4300 (c) 43
  35. 35.Best estimate of 5441 ÷ 89? (a) 600 (b) 60 (c) 6000
  36. 36.Best estimate of 3768 ÷ 74? (a) 540 (b) 54 (c) 5400
  37. 37.Best estimate of 2223 ÷ 29? (a) 740 (b) 7400 (c) 74
  38. 38.√38 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.3 (d) 6.1
  39. 39.√75 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.5 (d) 8.6
  40. 40.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.9 (d) 6.2

Answer key

  1. 45
  2. 5.9
  3. 9.6
  4. 5.1
  5. 27
  6. 24
  7. 77
  8. 37
  9. 7.1
  10. 9.3
  11. 23
  12. 59
  13. 7.6
  14. 6.9
  15. 67
  16. 78
  17. 62
  18. 4.9
  19. 9.4
  20. 88
  21. 36
  22. 6.6
  23. 40
  24. 45
  25. 6.3
  26. 47
  27. 24
  28. 4.8
  29. 16
  30. 45
  31. 21
  32. 5.7
  33. 42
  34. 43
  35. 60
  36. 54
  37. 74
  38. 6.2
  39. 8.7
  40. 6.1

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