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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 583 · 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.√98 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 9.7
  2. 2.√43 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.7
  3. 3.Best estimate of 2611 ÷ 52? (a) 5200 (b) 520 (c) 52
  4. 4.√85 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.4
  5. 5.Best estimate of 3739 ÷ 76? (a) 47 (b) 470 (c) 4700
  6. 6.Best estimate of 1203 ÷ 88? (a) 130 (b) 1300 (c) 13
  7. 7.√50 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.8 (d) 6.9
  8. 8.Best estimate of 2247 ÷ 66? (a) 3200 (b) 320 (c) 32
  9. 9.√48 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.9 (d) 6.6
  10. 10.Best estimate of 3650 ÷ 48? (a) 7300 (b) 73 (c) 730
  11. 11.Best estimate of 3240 ÷ 77? (a) 410 (b) 4100 (c) 41
  12. 12.√55 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.6 (d) 7.7
  13. 13.√52 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 6.9 (d) 7.0
  14. 14.√67 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.0 (d) 8.2
  15. 15.Best estimate of 4171 ÷ 82? (a) 520 (b) 52 (c) 5200
  16. 16.√20 to 1 decimal place? (a) 4.6 (b) 4.4 (c) 4.7 (d) 4.5
  17. 17.Best estimate of 559 ÷ 22? (a) 280 (b) 28 (c) 2800
  18. 18.Best estimate of 1149 ÷ 41? (a) 2900 (b) 29 (c) 290
  19. 19.√61 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.9
  20. 20.Best estimate of 569 ÷ 31? (a) 1900 (b) 190 (c) 19
  21. 21.√82 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.0 (d) 9.1
  22. 22.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.0
  23. 23.Best estimate of 3191 ÷ 58? (a) 530 (b) 53 (c) 5300
  24. 24.Best estimate of 5294 ÷ 57? (a) 88 (b) 880 (c) 8800
  25. 25.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  26. 26.Best estimate of 2274 ÷ 46? (a) 45 (b) 4500 (c) 450
  27. 27.Best estimate of 3144 ÷ 66? (a) 45 (b) 4500 (c) 450
  28. 28.√56 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.8 (d) 7.6
  29. 29.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.8 (d) 6.1
  30. 30.Best estimate of 3694 ÷ 76? (a) 46 (b) 4600 (c) 460
  31. 31.√23 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.7 (d) 4.8
  32. 32.Best estimate of 1430 ÷ 52? (a) 290 (b) 29 (c) 2900
  33. 33.√28 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.2 (d) 5.5
  34. 34.Best estimate of 3712 ÷ 57? (a) 620 (b) 6200 (c) 62
  35. 35.Best estimate of 3907 ÷ 56? (a) 6500 (b) 650 (c) 65
  36. 36.Best estimate of 5844 ÷ 77? (a) 730 (b) 7300 (c) 73
  37. 37.√72 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  38. 38.Best estimate of 1729 ÷ 23? (a) 860 (b) 8600 (c) 86
  39. 39.Best estimate of 1615 ÷ 39? (a) 400 (b) 40 (c) 4000
  40. 40.√69 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.4 (d) 8.5

Answer key

  1. 9.9
  2. 6.6
  3. 52
  4. 9.2
  5. 47
  6. 13
  7. 7.1
  8. 32
  9. 6.9
  10. 73
  11. 41
  12. 7.4
  13. 7.2
  14. 8.2
  15. 52
  16. 4.5
  17. 28
  18. 29
  19. 7.8
  20. 19
  21. 9.1
  22. 6.1
  23. 53
  24. 88
  25. 7.6
  26. 45
  27. 45
  28. 7.5
  29. 5.8
  30. 46
  31. 4.8
  32. 29
  33. 5.3
  34. 62
  35. 65
  36. 73
  37. 8.5
  38. 86
  39. 40
  40. 8.3

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