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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 820 · 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.√90 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.4 (d) 9.5
  2. 2.Best estimate of 1458 ÷ 32? (a) 49 (b) 490 (c) 4900
  3. 3.√87 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  4. 4.√76 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 8.6
  5. 5.Best estimate of 601 ÷ 29? (a) 20 (b) 2000 (c) 200
  6. 6.Best estimate of 5822 ÷ 76? (a) 73 (b) 730 (c) 7300
  7. 7.Best estimate of 2687 ÷ 53? (a) 540 (b) 5400 (c) 54
  8. 8.Best estimate of 957 ÷ 23? (a) 480 (b) 4800 (c) 48
  9. 9.Best estimate of 1446 ÷ 32? (a) 480 (b) 4800 (c) 48
  10. 10.Best estimate of 641 ÷ 36? (a) 1600 (b) 160 (c) 16
  11. 11.Best estimate of 1811 ÷ 36? (a) 45 (b) 450 (c) 4500
  12. 12.Best estimate of 1522 ÷ 38? (a) 38 (b) 380 (c) 3800
  13. 13.Best estimate of 4130 ÷ 62? (a) 69 (b) 690 (c) 6900
  14. 14.√84 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.3 (d) 9.1
  15. 15.√53 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.6 (d) 7.5
  16. 16.√96 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.8 (d) 9.6
  17. 17.√20 to 1 decimal place? (a) 4.6 (b) 4.4 (c) 4.7 (d) 4.5
  18. 18.√65 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 8.3
  19. 19.√34 to 1 decimal place? (a) 6.1 (b) 5.8 (c) 6.0 (d) 5.9
  20. 20.Best estimate of 2115 ÷ 23? (a) 10600 (b) 106 (c) 1060
  21. 21.√88 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.5 (d) 9.4
  22. 22.√59 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  23. 23.Best estimate of 2264 ÷ 31? (a) 750 (b) 75 (c) 7500
  24. 24.Best estimate of 3878 ÷ 43? (a) 9700 (b) 97 (c) 970
  25. 25.√51 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.2 (d) 7.4
  26. 26.√72 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.2 (d) 8.4
  27. 27.Best estimate of 827 ÷ 42? (a) 210 (b) 21 (c) 2100
  28. 28.√46 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.8 (d) 7.0
  29. 29.√38 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.1
  30. 30.√44 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.8 (d) 6.7
  31. 31.Best estimate of 3517 ÷ 41? (a) 880 (b) 8800 (c) 88
  32. 32.Best estimate of 1304 ÷ 62? (a) 22 (b) 220 (c) 2200
  33. 33.Best estimate of 5199 ÷ 72? (a) 740 (b) 7400 (c) 74
  34. 34.Best estimate of 1578 ÷ 21? (a) 79 (b) 790 (c) 7900
  35. 35.Best estimate of 2589 ÷ 42? (a) 650 (b) 65 (c) 6500
  36. 36.Best estimate of 2004 ÷ 71? (a) 29 (b) 290 (c) 2900
  37. 37.Best estimate of 2664 ÷ 29? (a) 8900 (b) 89 (c) 890
  38. 38.Best estimate of 2073 ÷ 48? (a) 4100 (b) 41 (c) 410
  39. 39.Best estimate of 1179 ÷ 31? (a) 390 (b) 3900 (c) 39
  40. 40.√52 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 7.2

Answer key

  1. 9.5
  2. 49
  3. 9.3
  4. 8.7
  5. 20
  6. 73
  7. 54
  8. 48
  9. 48
  10. 16
  11. 45
  12. 38
  13. 69
  14. 9.2
  15. 7.3
  16. 9.8
  17. 4.5
  18. 8.1
  19. 5.8
  20. 106
  21. 9.4
  22. 7.7
  23. 75
  24. 97
  25. 7.1
  26. 8.5
  27. 21
  28. 6.8
  29. 6.2
  30. 6.6
  31. 88
  32. 22
  33. 74
  34. 79
  35. 65
  36. 29
  37. 89
  38. 41
  39. 39
  40. 7.2

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