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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 139 · 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 4839 ÷ 89? (a) 54 (b) 5400 (c) 540
  2. 2.Best estimate of 2732 ÷ 33? (a) 9100 (b) 910 (c) 91
  3. 3.Best estimate of 2948 ÷ 31? (a) 9800 (b) 980 (c) 98
  4. 4.Best estimate of 8169 ÷ 86? (a) 9100 (b) 910 (c) 91
  5. 5.Best estimate of 4574 ÷ 78? (a) 570 (b) 5700 (c) 57
  6. 6.√59 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 7.6
  7. 7.Best estimate of 3942 ÷ 76? (a) 490 (b) 49 (c) 4900
  8. 8.Best estimate of 1585 ÷ 42? (a) 40 (b) 4000 (c) 400
  9. 9.Best estimate of 859 ÷ 32? (a) 29 (b) 2900 (c) 290
  10. 10.Best estimate of 527 ÷ 23? (a) 2600 (b) 26 (c) 260
  11. 11.Best estimate of 1218 ÷ 58? (a) 2000 (b) 200 (c) 20
  12. 12.Best estimate of 2649 ÷ 72? (a) 380 (b) 3800 (c) 38
  13. 13.Best estimate of 3434 ÷ 81? (a) 43 (b) 430 (c) 4300
  14. 14.Best estimate of 889 ÷ 48? (a) 18 (b) 180 (c) 1800
  15. 15.√38 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.4 (d) 6.1
  16. 16.Best estimate of 889 ÷ 27? (a) 3000 (b) 30 (c) 300
  17. 17.Best estimate of 3980 ÷ 54? (a) 800 (b) 80 (c) 8000
  18. 18.√96 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.8 (d) 9.6
  19. 19.Best estimate of 542 ÷ 34? (a) 180 (b) 18 (c) 1800
  20. 20.√94 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.7 (d) 9.9
  21. 21.Best estimate of 1587 ÷ 62? (a) 260 (b) 2600 (c) 26
  22. 22.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.1 (d) 9.2
  23. 23.Best estimate of 1683 ÷ 42? (a) 42 (b) 420 (c) 4200
  24. 24.√74 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.6 (d) 8.8
  25. 25.Best estimate of 597 ÷ 46? (a) 120 (b) 1200 (c) 12
  26. 26.Best estimate of 2686 ÷ 81? (a) 34 (b) 340 (c) 3400
  27. 27.Best estimate of 3148 ÷ 53? (a) 63 (b) 6300 (c) 630
  28. 28.Best estimate of 1655 ÷ 34? (a) 5500 (b) 550 (c) 55
  29. 29.Best estimate of 3593 ÷ 61? (a) 600 (b) 6000 (c) 60
  30. 30.√21 to 1 decimal place? (a) 4.5 (b) 4.3 (c) 4.6 (d) 4.4
  31. 31.Best estimate of 920 ÷ 38? (a) 230 (b) 23 (c) 2300
  32. 32.Best estimate of 2963 ÷ 66? (a) 4200 (b) 42 (c) 420
  33. 33.Best estimate of 495 ÷ 32? (a) 170 (b) 1700 (c) 17
  34. 34.√23 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.5 (d) 4.8
  35. 35.Best estimate of 862 ÷ 63? (a) 140 (b) 14 (c) 1400
  36. 36.√65 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  37. 37.Best estimate of 708 ÷ 23? (a) 350 (b) 3500 (c) 35
  38. 38.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 9.2
  39. 39.√80 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.1 (d) 9.0
  40. 40.Best estimate of 3942 ÷ 88? (a) 44 (b) 4400 (c) 440

Answer key

  1. 54
  2. 91
  3. 98
  4. 91
  5. 57
  6. 7.7
  7. 49
  8. 40
  9. 29
  10. 26
  11. 20
  12. 38
  13. 43
  14. 18
  15. 6.2
  16. 30
  17. 80
  18. 9.8
  19. 18
  20. 9.7
  21. 26
  22. 9.4
  23. 42
  24. 8.6
  25. 12
  26. 34
  27. 63
  28. 55
  29. 60
  30. 4.6
  31. 23
  32. 42
  33. 17
  34. 4.8
  35. 14
  36. 8.1
  37. 35
  38. 9.1
  39. 8.9
  40. 44

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