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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 11 · 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.√94 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.5 (d) 9.6
  2. 2.Best estimate of 4828 ÷ 86? (a) 5400 (b) 540 (c) 54
  3. 3.Best estimate of 3300 ÷ 51? (a) 660 (b) 66 (c) 6600
  4. 4.Best estimate of 3310 ÷ 82? (a) 4100 (b) 410 (c) 41
  5. 5.Best estimate of 6421 ÷ 83? (a) 80 (b) 8000 (c) 800
  6. 6.Best estimate of 1070 ÷ 31? (a) 3600 (b) 36 (c) 360
  7. 7.√76 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.9 (d) 8.8
  8. 8.Best estimate of 1795 ÷ 26? (a) 600 (b) 60 (c) 6000
  9. 9.Best estimate of 1154 ÷ 37? (a) 290 (b) 2900 (c) 29
  10. 10.Best estimate of 3878 ÷ 49? (a) 780 (b) 78 (c) 7800
  11. 11.Best estimate of 3861 ÷ 42? (a) 97 (b) 9700 (c) 970
  12. 12.√71 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.6
  13. 13.Best estimate of 7013 ÷ 76? (a) 880 (b) 8800 (c) 88
  14. 14.Best estimate of 5510 ÷ 64? (a) 9200 (b) 92 (c) 920
  15. 15.√31 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.3 (d) 5.4
  16. 16.Best estimate of 5249 ÷ 71? (a) 750 (b) 75 (c) 7500
  17. 17.Best estimate of 1652 ÷ 36? (a) 41 (b) 4100 (c) 410
  18. 18.Best estimate of 648 ÷ 24? (a) 320 (b) 32 (c) 3200
  19. 19.Best estimate of 4301 ÷ 56? (a) 720 (b) 72 (c) 7200
  20. 20.Best estimate of 1132 ÷ 52? (a) 230 (b) 2300 (c) 23
  21. 21.Best estimate of 1874 ÷ 22? (a) 940 (b) 9400 (c) 94
  22. 22.Best estimate of 440 ÷ 36? (a) 110 (b) 1100 (c) 11
  23. 23.Best estimate of 1469 ÷ 58? (a) 24 (b) 240 (c) 2400
  24. 24.Best estimate of 4780 ÷ 73? (a) 68 (b) 680 (c) 6800
  25. 25.Best estimate of 1341 ÷ 36? (a) 34 (b) 3400 (c) 340
  26. 26.Best estimate of 2694 ÷ 42? (a) 6700 (b) 670 (c) 67
  27. 27.Best estimate of 4143 ÷ 59? (a) 69 (b) 690 (c) 6900
  28. 28.√30 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  29. 29.√50 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  30. 30.Best estimate of 6892 ÷ 89? (a) 770 (b) 77 (c) 7700
  31. 31.Best estimate of 3998 ÷ 42? (a) 1000 (b) 10000 (c) 100
  32. 32.Best estimate of 1701 ÷ 28? (a) 5700 (b) 57 (c) 570
  33. 33.Best estimate of 2211 ÷ 46? (a) 4400 (b) 44 (c) 440
  34. 34.√56 to 1 decimal place? (a) 7.4 (b) 7.7 (c) 7.6 (d) 7.5
  35. 35.√29 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.3 (d) 5.2
  36. 36.Best estimate of 1313 ÷ 64? (a) 220 (b) 2200 (c) 22
  37. 37.Best estimate of 2488 ÷ 54? (a) 50 (b) 5000 (c) 500
  38. 38.Best estimate of 1971 ÷ 52? (a) 39 (b) 3900 (c) 390
  39. 39.Best estimate of 1115 ÷ 76? (a) 1400 (b) 14 (c) 140
  40. 40.√55 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.7 (d) 7.6

Answer key

  1. 9.7
  2. 54
  3. 66
  4. 41
  5. 80
  6. 36
  7. 8.7
  8. 60
  9. 29
  10. 78
  11. 97
  12. 8.4
  13. 88
  14. 92
  15. 5.6
  16. 75
  17. 41
  18. 32
  19. 72
  20. 23
  21. 94
  22. 11
  23. 24
  24. 68
  25. 34
  26. 67
  27. 69
  28. 5.5
  29. 7.1
  30. 77
  31. 100
  32. 57
  33. 44
  34. 7.5
  35. 5.4
  36. 22
  37. 50
  38. 39
  39. 14
  40. 7.4

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