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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 714 · 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 727 ÷ 59? (a) 1200 (b) 120 (c) 12
  2. 2.Best estimate of 2946 ÷ 48? (a) 5900 (b) 590 (c) 59
  3. 3.√22 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.0 (d) 4.7
  4. 4.Best estimate of 2790 ÷ 41? (a) 7000 (b) 700 (c) 70
  5. 5.Best estimate of 2120 ÷ 26? (a) 7100 (b) 710 (c) 71
  6. 6.√21 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.5
  7. 7.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  8. 8.Best estimate of 1480 ÷ 52? (a) 30 (b) 300 (c) 3000
  9. 9.√90 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  10. 10.Best estimate of 3147 ÷ 46? (a) 6300 (b) 63 (c) 630
  11. 11.Best estimate of 1741 ÷ 26? (a) 58 (b) 5800 (c) 580
  12. 12.Best estimate of 3405 ÷ 56? (a) 5700 (b) 57 (c) 570
  13. 13.Best estimate of 1145 ÷ 27? (a) 380 (b) 3800 (c) 38
  14. 14.Best estimate of 1834 ÷ 51? (a) 3700 (b) 370 (c) 37
  15. 15.Best estimate of 1152 ÷ 57? (a) 190 (b) 19 (c) 1900
  16. 16.Best estimate of 341 ÷ 28? (a) 1100 (b) 11 (c) 110
  17. 17.√82 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.0
  18. 18.√92 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.5 (d) 9.6
  19. 19.Best estimate of 2113 ÷ 32? (a) 7000 (b) 70 (c) 700
  20. 20.√38 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 6.2
  21. 21.Best estimate of 5399 ÷ 57? (a) 90 (b) 9000 (c) 900
  22. 22.√58 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.5 (d) 7.6
  23. 23.√67 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.0
  24. 24.Best estimate of 2399 ÷ 26? (a) 8000 (b) 80 (c) 800
  25. 25.Best estimate of 1119 ÷ 34? (a) 3700 (b) 370 (c) 37
  26. 26.Best estimate of 1983 ÷ 34? (a) 6600 (b) 66 (c) 660
  27. 27.Best estimate of 1628 ÷ 79? (a) 2000 (b) 200 (c) 20
  28. 28.Best estimate of 3919 ÷ 66? (a) 56 (b) 560 (c) 5600
  29. 29.Best estimate of 2567 ÷ 29? (a) 86 (b) 860 (c) 8600
  30. 30.Best estimate of 1594 ÷ 24? (a) 8000 (b) 800 (c) 80
  31. 31.√65 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 7.9
  32. 32.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.6 (d) 9.9
  33. 33.Best estimate of 3716 ÷ 42? (a) 930 (b) 9300 (c) 93
  34. 34.Best estimate of 3530 ÷ 39? (a) 880 (b) 88 (c) 8800
  35. 35.√51 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  36. 36.√30 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.4
  37. 37.Best estimate of 999 ÷ 56? (a) 1700 (b) 170 (c) 17
  38. 38.Best estimate of 1143 ÷ 62? (a) 1900 (b) 19 (c) 190
  39. 39.Best estimate of 3858 ÷ 48? (a) 7700 (b) 77 (c) 770
  40. 40.Best estimate of 2346 ÷ 49? (a) 47 (b) 470 (c) 4700

Answer key

  1. 12
  2. 59
  3. 4.7
  4. 70
  5. 71
  6. 4.6
  7. 7.4
  8. 30
  9. 9.5
  10. 63
  11. 58
  12. 57
  13. 38
  14. 37
  15. 19
  16. 11
  17. 9.1
  18. 9.6
  19. 70
  20. 6.2
  21. 90
  22. 7.6
  23. 8.2
  24. 80
  25. 37
  26. 66
  27. 20
  28. 56
  29. 86
  30. 80
  31. 8.1
  32. 9.9
  33. 93
  34. 88
  35. 7.1
  36. 5.5
  37. 17
  38. 19
  39. 77
  40. 47

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