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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 606 · 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.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.4
  2. 2.√65 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 8.2
  3. 3.√96 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.5 (d) 9.7
  4. 4.√29 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.4
  5. 5.√55 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.4 (d) 7.2
  6. 6.Best estimate of 2637 ÷ 31? (a) 88 (b) 880 (c) 8800
  7. 7.√67 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.0 (d) 8.3
  8. 8.Best estimate of 3904 ÷ 69? (a) 5600 (b) 560 (c) 56
  9. 9.Best estimate of 2012 ÷ 38? (a) 500 (b) 50 (c) 5000
  10. 10.Best estimate of 1553 ÷ 39? (a) 39 (b) 390 (c) 3900
  11. 11.√70 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.4 (d) 8.2
  12. 12.√76 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 9.0 (d) 8.8
  13. 13.Best estimate of 3924 ÷ 72? (a) 5600 (b) 56 (c) 560
  14. 14.√77 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.9 (d) 8.8
  15. 15.√98 to 1 decimal place? (a) 10.0 (b) 10.2 (c) 10.1 (d) 9.9
  16. 16.√71 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  17. 17.Best estimate of 2528 ÷ 56? (a) 42 (b) 420 (c) 4200
  18. 18.Best estimate of 1334 ÷ 24? (a) 6700 (b) 670 (c) 67
  19. 19.√45 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.7
  20. 20.Best estimate of 2113 ÷ 38? (a) 530 (b) 53 (c) 5300
  21. 21.Best estimate of 6152 ÷ 79? (a) 770 (b) 77 (c) 7700
  22. 22.Best estimate of 1205 ÷ 33? (a) 4000 (b) 400 (c) 40
  23. 23.Best estimate of 473 ÷ 32? (a) 16 (b) 160 (c) 1600
  24. 24.√69 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.3 (d) 8.2
  25. 25.Best estimate of 2553 ÷ 73? (a) 36 (b) 3600 (c) 360
  26. 26.Best estimate of 3659 ÷ 77? (a) 4600 (b) 46 (c) 460
  27. 27.Best estimate of 1012 ÷ 32? (a) 34 (b) 340 (c) 3400
  28. 28.Best estimate of 7070 ÷ 77? (a) 8800 (b) 880 (c) 88
  29. 29.√90 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.6 (d) 9.5
  30. 30.Best estimate of 1020 ÷ 52? (a) 200 (b) 20 (c) 2000
  31. 31.Best estimate of 2173 ÷ 49? (a) 4300 (b) 430 (c) 43
  32. 32.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.3 (d) 8.4
  33. 33.√51 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.2 (d) 6.9
  34. 34.Best estimate of 2248 ÷ 28? (a) 750 (b) 75 (c) 7500
  35. 35.Best estimate of 1118 ÷ 32? (a) 37 (b) 3700 (c) 370
  36. 36.√62 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 8.0 (d) 7.9
  37. 37.√59 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.7 (d) 7.5
  38. 38.√47 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 6.9 (d) 7.1
  39. 39.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.2 (d) 5.3
  40. 40.√34 to 1 decimal place? (a) 5.8 (b) 5.5 (c) 5.7 (d) 5.6

Answer key

  1. 5.1
  2. 8.1
  3. 9.8
  4. 5.4
  5. 7.4
  6. 88
  7. 8.2
  8. 56
  9. 50
  10. 39
  11. 8.4
  12. 8.7
  13. 56
  14. 8.8
  15. 9.9
  16. 8.4
  17. 42
  18. 67
  19. 6.7
  20. 53
  21. 77
  22. 40
  23. 16
  24. 8.3
  25. 36
  26. 46
  27. 34
  28. 88
  29. 9.5
  30. 20
  31. 43
  32. 8.6
  33. 7.1
  34. 75
  35. 37
  36. 7.9
  37. 7.7
  38. 6.9
  39. 5.5
  40. 5.8

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