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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 335 · 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 2021 ÷ 72? (a) 2900 (b) 290 (c) 29
  2. 2.√22 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.5
  3. 3.Best estimate of 6842 ÷ 72? (a) 9800 (b) 98 (c) 980
  4. 4.Best estimate of 1301 ÷ 46? (a) 2600 (b) 260 (c) 26
  5. 5.Best estimate of 4528 ÷ 77? (a) 570 (b) 5700 (c) 57
  6. 6.Best estimate of 1935 ÷ 24? (a) 97 (b) 970 (c) 9700
  7. 7.√46 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.5
  8. 8.Best estimate of 1024 ÷ 63? (a) 17 (b) 170 (c) 1700
  9. 9.Best estimate of 1571 ÷ 26? (a) 52 (b) 520 (c) 5200
  10. 10.√34 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.7 (d) 5.5
  11. 11.Best estimate of 1714 ÷ 58? (a) 290 (b) 2900 (c) 29
  12. 12.Best estimate of 2602 ÷ 29? (a) 8700 (b) 870 (c) 87
  13. 13.√86 to 1 decimal place? (a) 9.3 (b) 9.6 (c) 9.4 (d) 9.5
  14. 14.√26 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.0
  15. 15.Best estimate of 3224 ÷ 56? (a) 540 (b) 54 (c) 5400
  16. 16.√53 to 1 decimal place? (a) 7.0 (b) 7.3 (c) 7.2 (d) 7.1
  17. 17.√43 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.4 (d) 6.5
  18. 18.Best estimate of 1031 ÷ 82? (a) 13 (b) 130 (c) 1300
  19. 19.Best estimate of 1707 ÷ 56? (a) 28 (b) 280 (c) 2800
  20. 20.√69 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.5 (d) 8.4
  21. 21.√87 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.6 (d) 9.4
  22. 22.Best estimate of 3995 ÷ 52? (a) 800 (b) 80 (c) 8000
  23. 23.√96 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.5 (d) 9.7
  24. 24.√24 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 5.1 (d) 4.8
  25. 25.Best estimate of 2939 ÷ 77? (a) 37 (b) 370 (c) 3700
  26. 26.Best estimate of 1748 ÷ 73? (a) 2500 (b) 250 (c) 25
  27. 27.√83 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 8.8
  28. 28.Best estimate of 2210 ÷ 56? (a) 37 (b) 3700 (c) 370
  29. 29.√79 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 8.8
  30. 30.Best estimate of 2375 ÷ 56? (a) 4000 (b) 400 (c) 40
  31. 31.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  32. 32.Best estimate of 273 ÷ 22? (a) 140 (b) 14 (c) 1400
  33. 33.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.8 (d) 7.7
  34. 34.Best estimate of 1916 ÷ 86? (a) 210 (b) 2100 (c) 21
  35. 35.√47 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.7 (d) 6.6
  36. 36.Best estimate of 1870 ÷ 23? (a) 940 (b) 94 (c) 9400
  37. 37.√72 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.5 (d) 8.4
  38. 38.√45 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.6 (d) 6.9
  39. 39.Best estimate of 2861 ÷ 52? (a) 57 (b) 5700 (c) 570
  40. 40.√55 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.2 (d) 7.1

Answer key

  1. 29
  2. 4.7
  3. 98
  4. 26
  5. 57
  6. 97
  7. 6.8
  8. 17
  9. 52
  10. 5.8
  11. 29
  12. 87
  13. 9.3
  14. 5.1
  15. 54
  16. 7.3
  17. 6.6
  18. 13
  19. 28
  20. 8.3
  21. 9.3
  22. 80
  23. 9.8
  24. 4.9
  25. 37
  26. 25
  27. 9.1
  28. 37
  29. 8.9
  30. 40
  31. 5.9
  32. 14
  33. 7.5
  34. 21
  35. 6.9
  36. 94
  37. 8.5
  38. 6.7
  39. 57
  40. 7.4

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