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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 824 · 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 651 ÷ 43? (a) 160 (b) 1600 (c) 16
  2. 2.√63 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.6 (d) 7.7
  3. 3.√67 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.0
  4. 4.√58 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.5 (d) 7.6
  5. 5.Best estimate of 5405 ÷ 61? (a) 9000 (b) 900 (c) 90
  6. 6.Best estimate of 4017 ÷ 51? (a) 800 (b) 8000 (c) 80
  7. 7.Best estimate of 924 ÷ 36? (a) 23 (b) 230 (c) 2300
  8. 8.√76 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  9. 9.√66 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.0
  10. 10.Best estimate of 5239 ÷ 78? (a) 6500 (b) 650 (c) 65
  11. 11.Best estimate of 4065 ÷ 83? (a) 51 (b) 5100 (c) 510
  12. 12.Best estimate of 2980 ÷ 44? (a) 750 (b) 7500 (c) 75
  13. 13.Best estimate of 1141 ÷ 42? (a) 290 (b) 2900 (c) 29
  14. 14.Best estimate of 2456 ÷ 41? (a) 61 (b) 6100 (c) 610
  15. 15.√98 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.8 (d) 9.7
  16. 16.Best estimate of 1971 ÷ 33? (a) 6600 (b) 660 (c) 66
  17. 17.Best estimate of 4629 ÷ 51? (a) 9300 (b) 93 (c) 930
  18. 18.Best estimate of 6355 ÷ 79? (a) 790 (b) 79 (c) 7900
  19. 19.Best estimate of 2062 ÷ 31? (a) 6900 (b) 69 (c) 690
  20. 20.√45 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.8 (d) 6.7
  21. 21.√55 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.1 (d) 7.4
  22. 22.Best estimate of 1982 ÷ 67? (a) 28 (b) 2800 (c) 280
  23. 23.√42 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.4 (d) 6.6
  24. 24.√34 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.9 (d) 5.6
  25. 25.Best estimate of 4228 ÷ 52? (a) 85 (b) 850 (c) 8500
  26. 26.Best estimate of 1938 ÷ 34? (a) 65 (b) 650 (c) 6500
  27. 27.√53 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.3 (d) 7.2
  28. 28.√83 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 9.1
  29. 29.√27 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.0 (d) 4.9
  30. 30.√70 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.3 (d) 8.5
  31. 31.√59 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 8.0
  32. 32.√52 to 1 decimal place? (a) 7.5 (b) 7.2 (c) 7.3 (d) 7.4
  33. 33.Best estimate of 605 ÷ 29? (a) 2000 (b) 200 (c) 20
  34. 34.Best estimate of 2535 ÷ 42? (a) 6300 (b) 63 (c) 630
  35. 35.√21 to 1 decimal place? (a) 4.8 (b) 4.5 (c) 4.6 (d) 4.7
  36. 36.Best estimate of 1170 ÷ 64? (a) 20 (b) 2000 (c) 200
  37. 37.√44 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.5 (d) 6.8
  38. 38.Best estimate of 4192 ÷ 89? (a) 4700 (b) 470 (c) 47
  39. 39.Best estimate of 4861 ÷ 86? (a) 5400 (b) 54 (c) 540
  40. 40.√41 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.3

Answer key

  1. 16
  2. 7.9
  3. 8.2
  4. 7.6
  5. 90
  6. 80
  7. 23
  8. 8.7
  9. 8.1
  10. 65
  11. 51
  12. 75
  13. 29
  14. 61
  15. 9.9
  16. 66
  17. 93
  18. 79
  19. 69
  20. 6.7
  21. 7.4
  22. 28
  23. 6.5
  24. 5.8
  25. 85
  26. 65
  27. 7.3
  28. 9.1
  29. 5.2
  30. 8.4
  31. 7.7
  32. 7.2
  33. 20
  34. 63
  35. 4.6
  36. 20
  37. 6.6
  38. 47
  39. 54
  40. 6.4

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