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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 319 · 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 914 ÷ 34? (a) 30 (b) 300 (c) 3000
  2. 2.√62 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  3. 3.√53 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.3 (d) 7.2
  4. 4.Best estimate of 1447 ÷ 89? (a) 160 (b) 1600 (c) 16
  5. 5.√66 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  6. 6.Best estimate of 6237 ÷ 86? (a) 6900 (b) 69 (c) 690
  7. 7.Best estimate of 2083 ÷ 32? (a) 69 (b) 6900 (c) 690
  8. 8.√27 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.1 (d) 5.3
  9. 9.Best estimate of 6515 ÷ 69? (a) 93 (b) 9300 (c) 930
  10. 10.√29 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.4 (d) 5.5
  11. 11.√69 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.0 (d) 8.3
  12. 12.Best estimate of 4685 ÷ 51? (a) 940 (b) 9400 (c) 94
  13. 13.Best estimate of 394 ÷ 23? (a) 200 (b) 20 (c) 2000
  14. 14.Best estimate of 1966 ÷ 36? (a) 490 (b) 4900 (c) 49
  15. 15.√30 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.3 (d) 5.5
  16. 16.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  17. 17.Best estimate of 2098 ÷ 39? (a) 52 (b) 520 (c) 5200
  18. 18.√94 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.7
  19. 19.√40 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.5
  20. 20.Best estimate of 1661 ÷ 46? (a) 3300 (b) 33 (c) 330
  21. 21.Best estimate of 1609 ÷ 48? (a) 3200 (b) 320 (c) 32
  22. 22.Best estimate of 1662 ÷ 37? (a) 420 (b) 42 (c) 4200
  23. 23.Best estimate of 3379 ÷ 44? (a) 8400 (b) 84 (c) 840
  24. 24.√55 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.4 (d) 7.6
  25. 25.√75 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  26. 26.√58 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.5 (d) 7.3
  27. 27.Best estimate of 4248 ÷ 72? (a) 61 (b) 6100 (c) 610
  28. 28.Best estimate of 1576 ÷ 21? (a) 790 (b) 79 (c) 7900
  29. 29.Best estimate of 3778 ÷ 53? (a) 76 (b) 760 (c) 7600
  30. 30.Best estimate of 1867 ÷ 38? (a) 470 (b) 47 (c) 4700
  31. 31.Best estimate of 3496 ÷ 56? (a) 58 (b) 5800 (c) 580
  32. 32.Best estimate of 2142 ÷ 52? (a) 43 (b) 4300 (c) 430
  33. 33.√52 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.3 (d) 7.5
  34. 34.Best estimate of 5345 ÷ 89? (a) 590 (b) 5900 (c) 59
  35. 35.√78 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 9.1 (d) 8.9
  36. 36.Best estimate of 2452 ÷ 44? (a) 610 (b) 61 (c) 6100
  37. 37.Best estimate of 1973 ÷ 66? (a) 28 (b) 2800 (c) 280
  38. 38.Best estimate of 2748 ÷ 62? (a) 460 (b) 46 (c) 4600
  39. 39.Best estimate of 2168 ÷ 33? (a) 720 (b) 72 (c) 7200
  40. 40.Best estimate of 980 ÷ 67? (a) 1400 (b) 14 (c) 140

Answer key

  1. 30
  2. 7.9
  3. 7.3
  4. 16
  5. 8.1
  6. 69
  7. 69
  8. 5.2
  9. 93
  10. 5.4
  11. 8.3
  12. 94
  13. 20
  14. 49
  15. 5.5
  16. 8.6
  17. 52
  18. 9.7
  19. 6.3
  20. 33
  21. 32
  22. 42
  23. 84
  24. 7.4
  25. 8.7
  26. 7.6
  27. 61
  28. 79
  29. 76
  30. 47
  31. 58
  32. 43
  33. 7.2
  34. 59
  35. 8.8
  36. 61
  37. 28
  38. 46
  39. 72
  40. 14

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