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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 98 · 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 2720 ÷ 34? (a) 9100 (b) 91 (c) 910
  2. 2.Best estimate of 1719 ÷ 81? (a) 21 (b) 2100 (c) 210
  3. 3.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.8
  4. 4.√48 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  5. 5.Best estimate of 1565 ÷ 26? (a) 5200 (b) 520 (c) 52
  6. 6.√24 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.0 (d) 4.7
  7. 7.Best estimate of 1480 ÷ 26? (a) 49 (b) 4900 (c) 490
  8. 8.Best estimate of 426 ÷ 26? (a) 140 (b) 1400 (c) 14
  9. 9.Best estimate of 571 ÷ 33? (a) 190 (b) 19 (c) 1900
  10. 10.Best estimate of 605 ÷ 42? (a) 1500 (b) 15 (c) 150
  11. 11.Best estimate of 833 ÷ 56? (a) 140 (b) 1400 (c) 14
  12. 12.Best estimate of 3122 ÷ 52? (a) 62 (b) 6200 (c) 620
  13. 13.√20 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.4 (d) 4.6
  14. 14.√31 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.3
  15. 15.Best estimate of 5154 ÷ 56? (a) 86 (b) 8600 (c) 860
  16. 16.Best estimate of 3849 ÷ 44? (a) 96 (b) 9600 (c) 960
  17. 17.Best estimate of 3599 ÷ 89? (a) 400 (b) 4000 (c) 40
  18. 18.√77 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.8 (d) 8.9
  19. 19.Best estimate of 1259 ÷ 28? (a) 42 (b) 4200 (c) 420
  20. 20.√80 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 9.2
  21. 21.Best estimate of 2699 ÷ 61? (a) 45 (b) 4500 (c) 450
  22. 22.Best estimate of 1389 ÷ 26? (a) 460 (b) 4600 (c) 46
  23. 23.√35 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.8 (d) 5.6
  24. 24.Best estimate of 645 ÷ 31? (a) 22 (b) 2200 (c) 220
  25. 25.Best estimate of 1067 ÷ 39? (a) 27 (b) 270 (c) 2700
  26. 26.√79 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 8.8
  27. 27.√55 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.4 (d) 7.2
  28. 28.Best estimate of 767 ÷ 42? (a) 19 (b) 190 (c) 1900
  29. 29.√40 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.0 (d) 6.1
  30. 30.√43 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.5 (d) 6.4
  31. 31.Best estimate of 5931 ÷ 63? (a) 990 (b) 9900 (c) 99
  32. 32.√65 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 7.9
  33. 33.Best estimate of 3031 ÷ 43? (a) 76 (b) 760 (c) 7600
  34. 34.√75 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.7
  35. 35.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.4
  36. 36.√92 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.5 (d) 9.6
  37. 37.Best estimate of 1252 ÷ 31? (a) 42 (b) 4200 (c) 420
  38. 38.Best estimate of 5171 ÷ 81? (a) 6500 (b) 650 (c) 65
  39. 39.Best estimate of 5269 ÷ 72? (a) 750 (b) 7500 (c) 75
  40. 40.Best estimate of 6040 ÷ 71? (a) 8600 (b) 86 (c) 860

Answer key

  1. 91
  2. 21
  3. 8.6
  4. 6.9
  5. 52
  6. 4.9
  7. 49
  8. 14
  9. 19
  10. 15
  11. 14
  12. 62
  13. 4.5
  14. 5.6
  15. 86
  16. 96
  17. 40
  18. 8.8
  19. 42
  20. 8.9
  21. 45
  22. 46
  23. 5.9
  24. 22
  25. 27
  26. 8.9
  27. 7.4
  28. 19
  29. 6.3
  30. 6.6
  31. 99
  32. 8.1
  33. 76
  34. 8.7
  35. 5.3
  36. 9.6
  37. 42
  38. 65
  39. 75
  40. 86

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