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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 402 · 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.√26 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 4.9 (d) 5.1
  2. 2.Best estimate of 441 ÷ 21? (a) 22 (b) 2200 (c) 220
  3. 3.Best estimate of 2954 ÷ 42? (a) 740 (b) 7400 (c) 74
  4. 4.Best estimate of 4664 ÷ 64? (a) 78 (b) 780 (c) 7800
  5. 5.√71 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.5 (d) 8.3
  6. 6.√41 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.3 (d) 6.2
  7. 7.√28 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.3
  8. 8.Best estimate of 7246 ÷ 77? (a) 91 (b) 9100 (c) 910
  9. 9.Best estimate of 2269 ÷ 42? (a) 57 (b) 570 (c) 5700
  10. 10.Best estimate of 1117 ÷ 33? (a) 3700 (b) 370 (c) 37
  11. 11.√62 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 8.0
  12. 12.Best estimate of 1214 ÷ 29? (a) 40 (b) 400 (c) 4000
  13. 13.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.8
  14. 14.Best estimate of 1183 ÷ 48? (a) 24 (b) 240 (c) 2400
  15. 15.√40 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.4
  16. 16.Best estimate of 2878 ÷ 58? (a) 48 (b) 480 (c) 4800
  17. 17.√98 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  18. 18.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.0 (d) 7.1
  19. 19.Best estimate of 2335 ÷ 33? (a) 7800 (b) 780 (c) 78
  20. 20.Best estimate of 3333 ÷ 61? (a) 560 (b) 5600 (c) 56
  21. 21.Best estimate of 965 ÷ 29? (a) 320 (b) 3200 (c) 32
  22. 22.Best estimate of 1457 ÷ 48? (a) 2900 (b) 290 (c) 29
  23. 23.Best estimate of 2045 ÷ 86? (a) 230 (b) 23 (c) 2300
  24. 24.√58 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.7 (d) 7.5
  25. 25.Best estimate of 917 ÷ 57? (a) 150 (b) 1500 (c) 15
  26. 26.√50 to 1 decimal place? (a) 7.0 (b) 7.3 (c) 7.1 (d) 7.2
  27. 27.√84 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.5
  28. 28.Best estimate of 4327 ÷ 86? (a) 480 (b) 4800 (c) 48
  29. 29.√22 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.5 (d) 4.4
  30. 30.√85 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.2
  31. 31.Best estimate of 2267 ÷ 56? (a) 380 (b) 3800 (c) 38
  32. 32.Best estimate of 6839 ÷ 86? (a) 7600 (b) 760 (c) 76
  33. 33.Best estimate of 4777 ÷ 86? (a) 5300 (b) 53 (c) 530
  34. 34.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  35. 35.Best estimate of 1420 ÷ 42? (a) 360 (b) 36 (c) 3600
  36. 36.Best estimate of 3148 ÷ 33? (a) 10500 (b) 1050 (c) 105
  37. 37.Best estimate of 1656 ÷ 51? (a) 3300 (b) 33 (c) 330
  38. 38.Best estimate of 1656 ÷ 49? (a) 33 (b) 3300 (c) 330
  39. 39.Best estimate of 1780 ÷ 53? (a) 360 (b) 36 (c) 3600
  40. 40.Best estimate of 2462 ÷ 32? (a) 820 (b) 82 (c) 8200

Answer key

  1. 5.1
  2. 22
  3. 74
  4. 78
  5. 8.4
  6. 6.4
  7. 5.3
  8. 91
  9. 57
  10. 37
  11. 7.9
  12. 40
  13. 9.7
  14. 24
  15. 6.3
  16. 48
  17. 9.9
  18. 7.2
  19. 78
  20. 56
  21. 32
  22. 29
  23. 23
  24. 7.6
  25. 15
  26. 7.1
  27. 9.2
  28. 48
  29. 4.7
  30. 9.2
  31. 38
  32. 76
  33. 53
  34. 8.3
  35. 36
  36. 105
  37. 33
  38. 33
  39. 36
  40. 82

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