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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 800 · 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 6904 ÷ 79? (a) 8600 (b) 86 (c) 860
  2. 2.Best estimate of 2973 ÷ 36? (a) 74 (b) 7400 (c) 740
  3. 3.√53 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.2 (d) 7.1
  4. 4.√21 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.4 (d) 4.5
  5. 5.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.8 (d) 7.7
  6. 6.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  7. 7.Best estimate of 2550 ÷ 28? (a) 850 (b) 8500 (c) 85
  8. 8.Best estimate of 3586 ÷ 46? (a) 72 (b) 720 (c) 7200
  9. 9.Best estimate of 1274 ÷ 48? (a) 250 (b) 2500 (c) 25
  10. 10.Best estimate of 1712 ÷ 47? (a) 34 (b) 3400 (c) 340
  11. 11.Best estimate of 2628 ÷ 41? (a) 66 (b) 6600 (c) 660
  12. 12.Best estimate of 2195 ÷ 36? (a) 5500 (b) 55 (c) 550
  13. 13.Best estimate of 1489 ÷ 32? (a) 500 (b) 5000 (c) 50
  14. 14.Best estimate of 2496 ÷ 54? (a) 500 (b) 5000 (c) 50
  15. 15.Best estimate of 2686 ÷ 71? (a) 380 (b) 38 (c) 3800
  16. 16.√80 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.1 (d) 9.0
  17. 17.Best estimate of 2161 ÷ 34? (a) 72 (b) 720 (c) 7200
  18. 18.Best estimate of 2613 ÷ 39? (a) 65 (b) 6500 (c) 650
  19. 19.Best estimate of 5458 ÷ 76? (a) 680 (b) 6800 (c) 68
  20. 20.Best estimate of 3889 ÷ 88? (a) 43 (b) 430 (c) 4300
  21. 21.√29 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.5
  22. 22.Best estimate of 1044 ÷ 28? (a) 3500 (b) 35 (c) 350
  23. 23.Best estimate of 5131 ÷ 67? (a) 7300 (b) 73 (c) 730
  24. 24.√30 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.4
  25. 25.Best estimate of 1225 ÷ 23? (a) 610 (b) 6100 (c) 61
  26. 26.Best estimate of 2662 ÷ 56? (a) 440 (b) 4400 (c) 44
  27. 27.Best estimate of 5455 ÷ 88? (a) 61 (b) 610 (c) 6100
  28. 28.Best estimate of 4622 ÷ 76? (a) 5800 (b) 580 (c) 58
  29. 29.√87 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.3 (d) 9.4
  30. 30.√70 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.4 (d) 8.5
  31. 31.√42 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.5 (d) 6.7
  32. 32.Best estimate of 745 ÷ 37? (a) 19 (b) 190 (c) 1900
  33. 33.√27 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.4 (d) 5.2
  34. 34.Best estimate of 5007 ÷ 76? (a) 6300 (b) 630 (c) 63
  35. 35.Best estimate of 3119 ÷ 64? (a) 5200 (b) 520 (c) 52
  36. 36.√26 to 1 decimal place? (a) 5.3 (b) 5.0 (c) 5.1 (d) 5.2
  37. 37.Best estimate of 2329 ÷ 42? (a) 5800 (b) 580 (c) 58
  38. 38.Best estimate of 6048 ÷ 66? (a) 8600 (b) 860 (c) 86
  39. 39.Best estimate of 3184 ÷ 54? (a) 6400 (b) 640 (c) 64
  40. 40.Best estimate of 979 ÷ 62? (a) 16 (b) 160 (c) 1600

Answer key

  1. 86
  2. 74
  3. 7.3
  4. 4.6
  5. 7.5
  6. 7.4
  7. 85
  8. 72
  9. 25
  10. 34
  11. 66
  12. 55
  13. 50
  14. 50
  15. 38
  16. 8.9
  17. 72
  18. 65
  19. 68
  20. 43
  21. 5.4
  22. 35
  23. 73
  24. 5.5
  25. 61
  26. 44
  27. 61
  28. 58
  29. 9.3
  30. 8.4
  31. 6.5
  32. 19
  33. 5.2
  34. 63
  35. 52
  36. 5.1
  37. 58
  38. 86
  39. 64
  40. 16

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