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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 516 · 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 959 ÷ 74? (a) 140 (b) 14 (c) 1400
  2. 2.Best estimate of 2822 ÷ 32? (a) 9400 (b) 940 (c) 94
  3. 3.Best estimate of 1202 ÷ 41? (a) 30 (b) 300 (c) 3000
  4. 4.Best estimate of 2090 ÷ 69? (a) 30 (b) 300 (c) 3000
  5. 5.√62 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.7 (d) 7.8
  6. 6.Best estimate of 2287 ÷ 69? (a) 330 (b) 33 (c) 3300
  7. 7.√96 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.5 (d) 9.7
  8. 8.Best estimate of 1234 ÷ 68? (a) 180 (b) 18 (c) 1800
  9. 9.√71 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.4 (d) 8.3
  10. 10.√26 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  11. 11.Best estimate of 4242 ÷ 49? (a) 850 (b) 8500 (c) 85
  12. 12.√34 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.5
  13. 13.Best estimate of 1869 ÷ 42? (a) 47 (b) 470 (c) 4700
  14. 14.√76 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 9.0 (d) 8.9
  15. 15.Best estimate of 3310 ÷ 73? (a) 4700 (b) 470 (c) 47
  16. 16.Best estimate of 1226 ÷ 31? (a) 4100 (b) 410 (c) 41
  17. 17.Best estimate of 1860 ÷ 77? (a) 23 (b) 230 (c) 2300
  18. 18.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  19. 19.Best estimate of 953 ÷ 36? (a) 240 (b) 24 (c) 2400
  20. 20.√50 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  21. 21.Best estimate of 2229 ÷ 42? (a) 560 (b) 56 (c) 5600
  22. 22.Best estimate of 2282 ÷ 69? (a) 330 (b) 3300 (c) 33
  23. 23.√56 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.5 (d) 7.7
  24. 24.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.1
  25. 25.Best estimate of 6968 ÷ 77? (a) 87 (b) 870 (c) 8700
  26. 26.Best estimate of 1411 ÷ 43? (a) 350 (b) 3500 (c) 35
  27. 27.√92 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.6 (d) 9.7
  28. 28.Best estimate of 999 ÷ 26? (a) 3300 (b) 33 (c) 330
  29. 29.Best estimate of 1830 ÷ 24? (a) 92 (b) 920 (c) 9200
  30. 30.√24 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 5.2
  31. 31.Best estimate of 3225 ÷ 38? (a) 8100 (b) 810 (c) 81
  32. 32.Best estimate of 1906 ÷ 73? (a) 270 (b) 2700 (c) 27
  33. 33.√94 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.8
  34. 34.√45 to 1 decimal place? (a) 6.6 (b) 6.9 (c) 6.7 (d) 6.8
  35. 35.Best estimate of 1561 ÷ 62? (a) 260 (b) 2600 (c) 26
  36. 36.√85 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.1 (d) 9.0
  37. 37.Best estimate of 8170 ÷ 87? (a) 9100 (b) 91 (c) 910
  38. 38.√61 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.8 (d) 7.7
  39. 39.Best estimate of 1260 ÷ 32? (a) 420 (b) 4200 (c) 42
  40. 40.Best estimate of 597 ÷ 21? (a) 3000 (b) 30 (c) 300

Answer key

  1. 14
  2. 94
  3. 30
  4. 30
  5. 7.9
  6. 33
  7. 9.8
  8. 18
  9. 8.4
  10. 5.1
  11. 85
  12. 5.8
  13. 47
  14. 8.7
  15. 47
  16. 41
  17. 23
  18. 8.6
  19. 24
  20. 7.1
  21. 56
  22. 33
  23. 7.5
  24. 6.3
  25. 87
  26. 35
  27. 9.6
  28. 33
  29. 92
  30. 4.9
  31. 81
  32. 27
  33. 9.7
  34. 6.7
  35. 26
  36. 9.2
  37. 91
  38. 7.8
  39. 42
  40. 30

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