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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 896 · 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 6457 ÷ 74? (a) 92 (b) 920 (c) 9200
  2. 2.Best estimate of 4763 ÷ 56? (a) 79 (b) 790 (c) 7900
  3. 3.√42 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.5 (d) 6.7
  4. 4.√69 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.1 (d) 8.3
  5. 5.√65 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.8 (d) 7.9
  6. 6.Best estimate of 4390 ÷ 62? (a) 7300 (b) 730 (c) 73
  7. 7.Best estimate of 2175 ÷ 38? (a) 5400 (b) 54 (c) 540
  8. 8.Best estimate of 3455 ÷ 66? (a) 490 (b) 4900 (c) 49
  9. 9.Best estimate of 4697 ÷ 86? (a) 520 (b) 5200 (c) 52
  10. 10.√40 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.0 (d) 6.1
  11. 11.Best estimate of 2635 ÷ 57? (a) 440 (b) 44 (c) 4400
  12. 12.√61 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.9 (d) 7.8
  13. 13.Best estimate of 1429 ÷ 31? (a) 4800 (b) 48 (c) 480
  14. 14.Best estimate of 4696 ÷ 56? (a) 7800 (b) 78 (c) 780
  15. 15.Best estimate of 3684 ÷ 76? (a) 4600 (b) 460 (c) 46
  16. 16.Best estimate of 1971 ÷ 23? (a) 990 (b) 9900 (c) 99
  17. 17.Best estimate of 2611 ÷ 44? (a) 650 (b) 65 (c) 6500
  18. 18.√31 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.3 (d) 5.4
  19. 19.Best estimate of 5387 ÷ 68? (a) 77 (b) 7700 (c) 770
  20. 20.√98 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.7 (d) 9.9
  21. 21.Best estimate of 1631 ÷ 26? (a) 5400 (b) 540 (c) 54
  22. 22.Best estimate of 1917 ÷ 39? (a) 4800 (b) 480 (c) 48
  23. 23.Best estimate of 2816 ÷ 34? (a) 9400 (b) 940 (c) 94
  24. 24.√94 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  25. 25.√78 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.8 (d) 8.7
  26. 26.Best estimate of 1580 ÷ 88? (a) 18 (b) 1800 (c) 180
  27. 27.Best estimate of 1355 ÷ 23? (a) 6800 (b) 680 (c) 68
  28. 28.√22 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.5 (d) 4.6
  29. 29.Best estimate of 1095 ÷ 28? (a) 3700 (b) 370 (c) 37
  30. 30.Best estimate of 748 ÷ 24? (a) 370 (b) 3700 (c) 37
  31. 31.√58 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.6 (d) 7.8
  32. 32.√37 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.4
  33. 33.√27 to 1 decimal place? (a) 5.2 (b) 5.5 (c) 5.3 (d) 5.4
  34. 34.Best estimate of 2815 ÷ 81? (a) 350 (b) 3500 (c) 35
  35. 35.√92 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.7 (d) 9.8
  36. 36.√28 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 5.2 (d) 5.3
  37. 37.Best estimate of 1868 ÷ 77? (a) 230 (b) 23 (c) 2300
  38. 38.Best estimate of 758 ÷ 29? (a) 25 (b) 2500 (c) 250
  39. 39.Best estimate of 1933 ÷ 71? (a) 280 (b) 2800 (c) 28
  40. 40.Best estimate of 2218 ÷ 54? (a) 4400 (b) 44 (c) 440

Answer key

  1. 92
  2. 79
  3. 6.5
  4. 8.3
  5. 8.1
  6. 73
  7. 54
  8. 49
  9. 52
  10. 6.3
  11. 44
  12. 7.8
  13. 48
  14. 78
  15. 46
  16. 99
  17. 65
  18. 5.6
  19. 77
  20. 9.9
  21. 54
  22. 48
  23. 94
  24. 9.7
  25. 8.8
  26. 18
  27. 68
  28. 4.7
  29. 37
  30. 37
  31. 7.6
  32. 6.1
  33. 5.2
  34. 35
  35. 9.6
  36. 5.3
  37. 23
  38. 25
  39. 28
  40. 44

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