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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 642 · 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 1259 ÷ 21? (a) 6300 (b) 63 (c) 630
  2. 2.Best estimate of 1869 ÷ 29? (a) 6200 (b) 62 (c) 620
  3. 3.√69 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.1
  4. 4.Best estimate of 1468 ÷ 32? (a) 49 (b) 4900 (c) 490
  5. 5.Best estimate of 1731 ÷ 62? (a) 29 (b) 290 (c) 2900
  6. 6.Best estimate of 1180 ÷ 28? (a) 39 (b) 390 (c) 3900
  7. 7.√67 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.2
  8. 8.√24 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 4.9 (d) 4.7
  9. 9.√37 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.0 (d) 6.1
  10. 10.Best estimate of 2053 ÷ 52? (a) 410 (b) 41 (c) 4100
  11. 11.Best estimate of 1953 ÷ 89? (a) 22 (b) 2200 (c) 220
  12. 12.√20 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.5 (d) 4.6
  13. 13.√89 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  14. 14.Best estimate of 2374 ÷ 73? (a) 34 (b) 3400 (c) 340
  15. 15.√21 to 1 decimal place? (a) 4.6 (b) 4.4 (c) 4.7 (d) 4.5
  16. 16.Best estimate of 4793 ÷ 62? (a) 8000 (b) 80 (c) 800
  17. 17.√80 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  18. 18.Best estimate of 4834 ÷ 67? (a) 69 (b) 690 (c) 6900
  19. 19.Best estimate of 5094 ÷ 63? (a) 8500 (b) 85 (c) 850
  20. 20.√70 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.4 (d) 8.5
  21. 21.Best estimate of 2167 ÷ 53? (a) 430 (b) 4300 (c) 43
  22. 22.Best estimate of 1425 ÷ 88? (a) 1600 (b) 16 (c) 160
  23. 23.Best estimate of 2938 ÷ 86? (a) 33 (b) 330 (c) 3300
  24. 24.√51 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.1 (d) 7.4
  25. 25.√29 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.4
  26. 26.Best estimate of 6873 ÷ 78? (a) 8600 (b) 86 (c) 860
  27. 27.√58 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.5 (d) 7.7
  28. 28.√38 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.3 (d) 6.1
  29. 29.√75 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.5
  30. 30.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.1 (d) 10.0
  31. 31.Best estimate of 2680 ÷ 57? (a) 4500 (b) 45 (c) 450
  32. 32.Best estimate of 899 ÷ 42? (a) 220 (b) 2200 (c) 22
  33. 33.Best estimate of 4045 ÷ 72? (a) 58 (b) 580 (c) 5800
  34. 34.Best estimate of 4505 ÷ 53? (a) 9000 (b) 90 (c) 900
  35. 35.Best estimate of 2336 ÷ 26? (a) 78 (b) 7800 (c) 780
  36. 36.Best estimate of 2528 ÷ 32? (a) 84 (b) 840 (c) 8400
  37. 37.Best estimate of 1292 ÷ 77? (a) 160 (b) 16 (c) 1600
  38. 38.√72 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.4 (d) 8.6
  39. 39.√27 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.0 (d) 4.9
  40. 40.Best estimate of 5094 ÷ 57? (a) 850 (b) 8500 (c) 85

Answer key

  1. 63
  2. 62
  3. 8.3
  4. 49
  5. 29
  6. 39
  7. 8.2
  8. 4.9
  9. 6.1
  10. 41
  11. 22
  12. 4.5
  13. 9.4
  14. 34
  15. 4.6
  16. 80
  17. 8.9
  18. 69
  19. 85
  20. 8.4
  21. 43
  22. 16
  23. 33
  24. 7.1
  25. 5.4
  26. 86
  27. 7.6
  28. 6.2
  29. 8.7
  30. 9.8
  31. 45
  32. 22
  33. 58
  34. 90
  35. 78
  36. 84
  37. 16
  38. 8.5
  39. 5.2
  40. 85

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