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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 611 · 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.√96 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  2. 2.Best estimate of 1290 ÷ 22? (a) 65 (b) 6500 (c) 650
  3. 3.√75 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  4. 4.√27 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.0 (d) 5.2
  5. 5.√83 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 9.2
  6. 6.Best estimate of 1923 ÷ 33? (a) 64 (b) 640 (c) 6400
  7. 7.Best estimate of 2247 ÷ 44? (a) 560 (b) 5600 (c) 56
  8. 8.√26 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.2 (d) 5.1
  9. 9.Best estimate of 4165 ÷ 86? (a) 460 (b) 4600 (c) 46
  10. 10.√23 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 4.9 (d) 5.0
  11. 11.Best estimate of 3122 ÷ 72? (a) 45 (b) 450 (c) 4500
  12. 12.Best estimate of 1860 ÷ 52? (a) 370 (b) 3700 (c) 37
  13. 13.Best estimate of 8284 ÷ 89? (a) 92 (b) 9200 (c) 920
  14. 14.Best estimate of 1456 ÷ 32? (a) 4900 (b) 49 (c) 490
  15. 15.Best estimate of 971 ÷ 73? (a) 14 (b) 140 (c) 1400
  16. 16.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.4
  17. 17.Best estimate of 2844 ÷ 42? (a) 7100 (b) 71 (c) 710
  18. 18.√48 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.0 (d) 7.1
  19. 19.Best estimate of 1308 ÷ 28? (a) 440 (b) 4400 (c) 44
  20. 20.Best estimate of 1638 ÷ 48? (a) 3300 (b) 33 (c) 330
  21. 21.Best estimate of 576 ÷ 41? (a) 14 (b) 140 (c) 1400
  22. 22.Best estimate of 2386 ÷ 72? (a) 3400 (b) 34 (c) 340
  23. 23.Best estimate of 2764 ÷ 89? (a) 3100 (b) 310 (c) 31
  24. 24.Best estimate of 5610 ÷ 82? (a) 7000 (b) 700 (c) 70
  25. 25.Best estimate of 5908 ÷ 83? (a) 7400 (b) 740 (c) 74
  26. 26.√77 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.8 (d) 8.7
  27. 27.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.1 (d) 8.2
  28. 28.Best estimate of 2841 ÷ 44? (a) 710 (b) 7100 (c) 71
  29. 29.Best estimate of 3197 ÷ 62? (a) 530 (b) 5300 (c) 53
  30. 30.Best estimate of 3389 ÷ 88? (a) 38 (b) 3800 (c) 380
  31. 31.√88 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  32. 32.Best estimate of 1808 ÷ 82? (a) 230 (b) 2300 (c) 23
  33. 33.Best estimate of 2553 ÷ 51? (a) 510 (b) 51 (c) 5100
  34. 34.Best estimate of 4011 ÷ 52? (a) 800 (b) 8000 (c) 80
  35. 35.Best estimate of 272 ÷ 22? (a) 14 (b) 140 (c) 1400
  36. 36.√38 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.3 (d) 6.2
  37. 37.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.1 (d) 8.0
  38. 38.Best estimate of 2316 ÷ 34? (a) 77 (b) 770 (c) 7700
  39. 39.Best estimate of 2623 ÷ 56? (a) 4400 (b) 44 (c) 440
  40. 40.Best estimate of 1268 ÷ 36? (a) 3200 (b) 320 (c) 32

Answer key

  1. 9.8
  2. 65
  3. 8.7
  4. 5.2
  5. 9.1
  6. 64
  7. 56
  8. 5.1
  9. 46
  10. 4.8
  11. 45
  12. 37
  13. 92
  14. 49
  15. 14
  16. 9.6
  17. 71
  18. 6.9
  19. 44
  20. 33
  21. 14
  22. 34
  23. 31
  24. 70
  25. 74
  26. 8.8
  27. 8.4
  28. 71
  29. 53
  30. 38
  31. 9.4
  32. 23
  33. 51
  34. 80
  35. 14
  36. 6.2
  37. 7.8
  38. 77
  39. 44
  40. 32

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