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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 131 · 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.√42 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.3 (d) 6.5
  2. 2.Best estimate of 2842 ÷ 66? (a) 4100 (b) 41 (c) 410
  3. 3.√77 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.8 (d) 8.6
  4. 4.√74 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.7
  5. 5.√67 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.5
  6. 6.Best estimate of 2153 ÷ 33? (a) 720 (b) 7200 (c) 72
  7. 7.√61 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.8 (d) 7.9
  8. 8.Best estimate of 1470 ÷ 32? (a) 49 (b) 4900 (c) 490
  9. 9.Best estimate of 2395 ÷ 56? (a) 40 (b) 400 (c) 4000
  10. 10.Best estimate of 1737 ÷ 83? (a) 22 (b) 220 (c) 2200
  11. 11.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.1 (d) 10.0
  12. 12.Best estimate of 1185 ÷ 47? (a) 2400 (b) 24 (c) 240
  13. 13.√21 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.9 (d) 4.6
  14. 14.Best estimate of 711 ÷ 21? (a) 360 (b) 3600 (c) 36
  15. 15.Best estimate of 1146 ÷ 38? (a) 29 (b) 2900 (c) 290
  16. 16.√58 to 1 decimal place? (a) 7.4 (b) 7.7 (c) 7.5 (d) 7.6
  17. 17.√65 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  18. 18.Best estimate of 4368 ÷ 64? (a) 7300 (b) 73 (c) 730
  19. 19.Best estimate of 3482 ÷ 72? (a) 50 (b) 5000 (c) 500
  20. 20.Best estimate of 3518 ÷ 84? (a) 4400 (b) 44 (c) 440
  21. 21.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  22. 22.Best estimate of 2731 ÷ 42? (a) 68 (b) 6800 (c) 680
  23. 23.Best estimate of 1672 ÷ 53? (a) 3300 (b) 33 (c) 330
  24. 24.√80 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 8.8 (d) 9.0
  25. 25.Best estimate of 2249 ÷ 47? (a) 450 (b) 4500 (c) 45
  26. 26.Best estimate of 3336 ÷ 66? (a) 48 (b) 4800 (c) 480
  27. 27.Best estimate of 3825 ÷ 42? (a) 960 (b) 9600 (c) 96
  28. 28.Best estimate of 2294 ÷ 41? (a) 570 (b) 57 (c) 5700
  29. 29.Best estimate of 5725 ÷ 73? (a) 8200 (b) 820 (c) 82
  30. 30.Best estimate of 4696 ÷ 52? (a) 9400 (b) 94 (c) 940
  31. 31.√37 to 1 decimal place? (a) 5.8 (b) 6.1 (c) 5.9 (d) 6.0
  32. 32.Best estimate of 2632 ÷ 29? (a) 8800 (b) 88 (c) 880
  33. 33.Best estimate of 1165 ÷ 43? (a) 29 (b) 2900 (c) 290
  34. 34.Best estimate of 912 ÷ 43? (a) 23 (b) 230 (c) 2300
  35. 35.Best estimate of 950 ÷ 48? (a) 19 (b) 1900 (c) 190
  36. 36.√22 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.4 (d) 4.6
  37. 37.√69 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.2
  38. 38.Best estimate of 2387 ÷ 76? (a) 300 (b) 3000 (c) 30
  39. 39.Best estimate of 1478 ÷ 53? (a) 30 (b) 3000 (c) 300
  40. 40.√40 to 1 decimal place? (a) 6.4 (b) 6.2 (c) 6.5 (d) 6.3

Answer key

  1. 6.5
  2. 41
  3. 8.8
  4. 8.6
  5. 8.2
  6. 72
  7. 7.8
  8. 49
  9. 40
  10. 22
  11. 9.8
  12. 24
  13. 4.6
  14. 36
  15. 29
  16. 7.6
  17. 8.1
  18. 73
  19. 50
  20. 44
  21. 9.7
  22. 68
  23. 33
  24. 8.9
  25. 45
  26. 48
  27. 96
  28. 57
  29. 82
  30. 94
  31. 6.1
  32. 88
  33. 29
  34. 23
  35. 19
  36. 4.7
  37. 8.3
  38. 30
  39. 30
  40. 6.3

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