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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 99 · 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 6628 ÷ 86? (a) 740 (b) 74 (c) 7400
  2. 2.Best estimate of 4028 ÷ 66? (a) 5800 (b) 580 (c) 58
  3. 3.√34 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.8 (d) 5.6
  4. 4.Best estimate of 768 ÷ 36? (a) 1900 (b) 19 (c) 190
  5. 5.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.0 (d) 5.1
  6. 6.Best estimate of 4335 ÷ 48? (a) 87 (b) 870 (c) 8700
  7. 7.Best estimate of 1577 ÷ 48? (a) 3200 (b) 320 (c) 32
  8. 8.√76 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 8.7
  9. 9.Best estimate of 2284 ÷ 62? (a) 3800 (b) 38 (c) 380
  10. 10.√23 to 1 decimal place? (a) 4.9 (b) 4.6 (c) 4.7 (d) 4.8
  11. 11.Best estimate of 3813 ÷ 59? (a) 640 (b) 64 (c) 6400
  12. 12.Best estimate of 2291 ÷ 48? (a) 460 (b) 46 (c) 4600
  13. 13.Best estimate of 1010 ÷ 42? (a) 25 (b) 250 (c) 2500
  14. 14.Best estimate of 510 ÷ 31? (a) 170 (b) 17 (c) 1700
  15. 15.√79 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  16. 16.Best estimate of 1168 ÷ 26? (a) 3900 (b) 390 (c) 39
  17. 17.Best estimate of 975 ÷ 37? (a) 24 (b) 240 (c) 2400
  18. 18.Best estimate of 3494 ÷ 73? (a) 500 (b) 50 (c) 5000
  19. 19.Best estimate of 3987 ÷ 43? (a) 100 (b) 1000 (c) 10000
  20. 20.√69 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.5 (d) 8.3
  21. 21.Best estimate of 1477 ÷ 34? (a) 490 (b) 49 (c) 4900
  22. 22.Best estimate of 1221 ÷ 52? (a) 240 (b) 2400 (c) 24
  23. 23.√22 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.9 (d) 4.6
  24. 24.√65 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  25. 25.Best estimate of 529 ÷ 28? (a) 18 (b) 180 (c) 1800
  26. 26.Best estimate of 2169 ÷ 29? (a) 7200 (b) 720 (c) 72
  27. 27.Best estimate of 4516 ÷ 78? (a) 560 (b) 5600 (c) 56
  28. 28.√56 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.8 (d) 7.7
  29. 29.√87 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 9.3
  30. 30.√58 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.9
  31. 31.Best estimate of 2092 ÷ 64? (a) 350 (b) 35 (c) 3500
  32. 32.Best estimate of 2854 ÷ 46? (a) 5700 (b) 57 (c) 570
  33. 33.√35 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.2 (d) 5.9
  34. 34.√31 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.6 (d) 5.8
  35. 35.Best estimate of 3621 ÷ 64? (a) 600 (b) 6000 (c) 60
  36. 36.Best estimate of 5064 ÷ 72? (a) 72 (b) 7200 (c) 720
  37. 37.√63 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 8.0 (d) 7.8
  38. 38.√98 to 1 decimal place? (a) 10.2 (b) 10.1 (c) 10.0 (d) 9.9
  39. 39.Best estimate of 3233 ÷ 72? (a) 46 (b) 460 (c) 4600
  40. 40.Best estimate of 980 ÷ 41? (a) 2500 (b) 250 (c) 25

Answer key

  1. 74
  2. 58
  3. 5.8
  4. 19
  5. 5.1
  6. 87
  7. 32
  8. 8.7
  9. 38
  10. 4.8
  11. 64
  12. 46
  13. 25
  14. 17
  15. 8.9
  16. 39
  17. 24
  18. 50
  19. 100
  20. 8.3
  21. 49
  22. 24
  23. 4.7
  24. 8.1
  25. 18
  26. 72
  27. 56
  28. 7.5
  29. 9.3
  30. 7.6
  31. 35
  32. 57
  33. 5.9
  34. 5.6
  35. 60
  36. 72
  37. 7.9
  38. 9.9
  39. 46
  40. 25

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