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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 485 · 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 1715 ÷ 73? (a) 250 (b) 25 (c) 2500
  2. 2.Best estimate of 2784 ÷ 34? (a) 9300 (b) 93 (c) 930
  3. 3.Best estimate of 7164 ÷ 88? (a) 800 (b) 80 (c) 8000
  4. 4.Best estimate of 1190 ÷ 52? (a) 2400 (b) 240 (c) 24
  5. 5.Best estimate of 2577 ÷ 34? (a) 860 (b) 8600 (c) 86
  6. 6.Best estimate of 7679 ÷ 86? (a) 85 (b) 850 (c) 8500
  7. 7.√32 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.7
  8. 8.√84 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.4 (d) 9.3
  9. 9.Best estimate of 5424 ÷ 64? (a) 9000 (b) 900 (c) 90
  10. 10.Best estimate of 4938 ÷ 52? (a) 99 (b) 9900 (c) 990
  11. 11.Best estimate of 5380 ÷ 79? (a) 670 (b) 67 (c) 6700
  12. 12.√83 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 9.2
  13. 13.√26 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 4.9 (d) 5.1
  14. 14.√66 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  15. 15.√90 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.5 (d) 9.6
  16. 16.Best estimate of 1776 ÷ 78? (a) 220 (b) 2200 (c) 22
  17. 17.Best estimate of 5929 ÷ 73? (a) 8500 (b) 850 (c) 85
  18. 18.Best estimate of 2490 ÷ 34? (a) 830 (b) 8300 (c) 83
  19. 19.√69 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.2 (d) 8.4
  20. 20.Best estimate of 4291 ÷ 72? (a) 6100 (b) 610 (c) 61
  21. 21.Best estimate of 3765 ÷ 62? (a) 6300 (b) 63 (c) 630
  22. 22.√37 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.1 (d) 6.0
  23. 23.√82 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 9.2
  24. 24.√98 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.9 (d) 9.8
  25. 25.√75 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.6 (d) 8.5
  26. 26.√51 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  27. 27.Best estimate of 2705 ÷ 37? (a) 680 (b) 68 (c) 6800
  28. 28.Best estimate of 1028 ÷ 36? (a) 2600 (b) 260 (c) 26
  29. 29.Best estimate of 2399 ÷ 54? (a) 4800 (b) 480 (c) 48
  30. 30.Best estimate of 1760 ÷ 31? (a) 59 (b) 5900 (c) 590
  31. 31.Best estimate of 1232 ÷ 62? (a) 21 (b) 2100 (c) 210
  32. 32.√53 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  33. 33.Best estimate of 2019 ÷ 24? (a) 10100 (b) 101 (c) 1010
  34. 34.Best estimate of 2355 ÷ 82? (a) 2900 (b) 290 (c) 29
  35. 35.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  36. 36.Best estimate of 1513 ÷ 33? (a) 500 (b) 5000 (c) 50
  37. 37.√89 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.4
  38. 38.Best estimate of 2582 ÷ 77? (a) 3200 (b) 320 (c) 32
  39. 39.√42 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.5 (d) 6.6
  40. 40.Best estimate of 5261 ÷ 59? (a) 88 (b) 8800 (c) 880

Answer key

  1. 25
  2. 93
  3. 80
  4. 24
  5. 86
  6. 85
  7. 5.7
  8. 9.2
  9. 90
  10. 99
  11. 67
  12. 9.1
  13. 5.1
  14. 8.1
  15. 9.5
  16. 22
  17. 85
  18. 83
  19. 8.3
  20. 61
  21. 63
  22. 6.1
  23. 9.1
  24. 9.9
  25. 8.7
  26. 7.1
  27. 68
  28. 26
  29. 48
  30. 59
  31. 21
  32. 7.3
  33. 101
  34. 29
  35. 5.6
  36. 50
  37. 9.4
  38. 32
  39. 6.5
  40. 88

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