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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 547 · 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.√37 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.1 (d) 6.2
  2. 2.Best estimate of 2002 ÷ 23? (a) 1000 (b) 10000 (c) 100
  3. 3.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  4. 4.Best estimate of 3182 ÷ 43? (a) 8000 (b) 800 (c) 80
  5. 5.Best estimate of 3091 ÷ 41? (a) 770 (b) 7700 (c) 77
  6. 6.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.5 (d) 5.7
  7. 7.Best estimate of 1625 ÷ 36? (a) 410 (b) 4100 (c) 41
  8. 8.√80 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 8.9 (d) 9.1
  9. 9.√90 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.5 (d) 9.3
  10. 10.√94 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.8
  11. 11.Best estimate of 3028 ÷ 32? (a) 1010 (b) 101 (c) 10100
  12. 12.Best estimate of 1885 ÷ 36? (a) 47 (b) 470 (c) 4700
  13. 13.Best estimate of 2321 ÷ 26? (a) 77 (b) 770 (c) 7700
  14. 14.√75 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.6 (d) 8.5
  15. 15.Best estimate of 6858 ÷ 84? (a) 86 (b) 860 (c) 8600
  16. 16.Best estimate of 3108 ÷ 81? (a) 390 (b) 3900 (c) 39
  17. 17.Best estimate of 2049 ÷ 88? (a) 2300 (b) 23 (c) 230
  18. 18.√50 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.1 (d) 7.0
  19. 19.√70 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.1
  20. 20.Best estimate of 5091 ÷ 86? (a) 5700 (b) 570 (c) 57
  21. 21.√77 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  22. 22.Best estimate of 2757 ÷ 62? (a) 460 (b) 46 (c) 4600
  23. 23.Best estimate of 1450 ÷ 56? (a) 2400 (b) 240 (c) 24
  24. 24.Best estimate of 2580 ÷ 46? (a) 52 (b) 5200 (c) 520
  25. 25.Best estimate of 989 ÷ 52? (a) 2000 (b) 20 (c) 200
  26. 26.√29 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.4 (d) 5.2
  27. 27.Best estimate of 560 ÷ 36? (a) 140 (b) 1400 (c) 14
  28. 28.Best estimate of 2028 ÷ 41? (a) 51 (b) 5100 (c) 510
  29. 29.Best estimate of 5080 ÷ 76? (a) 640 (b) 6400 (c) 64
  30. 30.√85 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.3 (d) 9.4
  31. 31.Best estimate of 3132 ÷ 46? (a) 63 (b) 630 (c) 6300
  32. 32.Best estimate of 1636 ÷ 86? (a) 18 (b) 1800 (c) 180
  33. 33.√86 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.3 (d) 9.4
  34. 34.Best estimate of 7186 ÷ 89? (a) 800 (b) 8000 (c) 80
  35. 35.√96 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.9 (d) 9.7
  36. 36.Best estimate of 800 ÷ 36? (a) 200 (b) 2000 (c) 20
  37. 37.√28 to 1 decimal place? (a) 5.6 (b) 5.3 (c) 5.5 (d) 5.4
  38. 38.Best estimate of 4367 ÷ 88? (a) 4900 (b) 49 (c) 490
  39. 39.Best estimate of 1204 ÷ 28? (a) 400 (b) 40 (c) 4000
  40. 40.Best estimate of 1647 ÷ 47? (a) 330 (b) 33 (c) 3300

Answer key

  1. 6.1
  2. 100
  3. 5.6
  4. 80
  5. 77
  6. 5.8
  7. 41
  8. 8.9
  9. 9.5
  10. 9.7
  11. 101
  12. 47
  13. 77
  14. 8.7
  15. 86
  16. 39
  17. 23
  18. 7.1
  19. 8.4
  20. 57
  21. 8.8
  22. 46
  23. 24
  24. 52
  25. 20
  26. 5.4
  27. 14
  28. 51
  29. 64
  30. 9.2
  31. 63
  32. 18
  33. 9.3
  34. 80
  35. 9.8
  36. 20
  37. 5.3
  38. 49
  39. 40
  40. 33

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