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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 593 · 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 2388 ÷ 28? (a) 8000 (b) 800 (c) 80
  2. 2.Best estimate of 2345 ÷ 56? (a) 390 (b) 39 (c) 3900
  3. 3.√44 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.6 (d) 6.7
  4. 4.Best estimate of 599 ÷ 24? (a) 300 (b) 3000 (c) 30
  5. 5.Best estimate of 4729 ÷ 51? (a) 9500 (b) 950 (c) 95
  6. 6.Best estimate of 3856 ÷ 88? (a) 430 (b) 4300 (c) 43
  7. 7.√40 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.6 (d) 6.4
  8. 8.Best estimate of 586 ÷ 28? (a) 2000 (b) 200 (c) 20
  9. 9.√42 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.7
  10. 10.Best estimate of 5066 ÷ 79? (a) 6300 (b) 630 (c) 63
  11. 11.Best estimate of 2576 ÷ 37? (a) 640 (b) 64 (c) 6400
  12. 12.Best estimate of 1923 ÷ 52? (a) 380 (b) 3800 (c) 38
  13. 13.Best estimate of 4941 ÷ 64? (a) 8200 (b) 820 (c) 82
  14. 14.Best estimate of 652 ÷ 31? (a) 220 (b) 2200 (c) 22
  15. 15.Best estimate of 1696 ÷ 61? (a) 280 (b) 2800 (c) 28
  16. 16.√27 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.1 (d) 5.4
  17. 17.√58 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.7 (d) 7.8
  18. 18.Best estimate of 4495 ÷ 58? (a) 7500 (b) 75 (c) 750
  19. 19.√61 to 1 decimal place? (a) 8.1 (b) 7.8 (c) 7.9 (d) 8.0
  20. 20.Best estimate of 1288 ÷ 23? (a) 6400 (b) 64 (c) 640
  21. 21.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  22. 22.√55 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.2 (d) 7.4
  23. 23.√48 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 7.2 (d) 7.0
  24. 24.Best estimate of 1939 ÷ 66? (a) 2800 (b) 28 (c) 280
  25. 25.Best estimate of 4893 ÷ 62? (a) 820 (b) 8200 (c) 82
  26. 26.√45 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  27. 27.√43 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.6 (d) 6.5
  28. 28.Best estimate of 7775 ÷ 89? (a) 860 (b) 8600 (c) 86
  29. 29.√22 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 4.7 (d) 4.9
  30. 30.√69 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  31. 31.Best estimate of 1929 ÷ 76? (a) 240 (b) 24 (c) 2400
  32. 32.Best estimate of 2876 ÷ 82? (a) 3600 (b) 360 (c) 36
  33. 33.√96 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 10.0 (d) 9.8
  34. 34.Best estimate of 1526 ÷ 68? (a) 220 (b) 22 (c) 2200
  35. 35.Best estimate of 2702 ÷ 72? (a) 3900 (b) 390 (c) 39
  36. 36.Best estimate of 4145 ÷ 86? (a) 46 (b) 4600 (c) 460
  37. 37.√37 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 6.2
  38. 38.Best estimate of 2144 ÷ 82? (a) 2700 (b) 270 (c) 27
  39. 39.Best estimate of 5037 ÷ 83? (a) 630 (b) 6300 (c) 63
  40. 40.Best estimate of 2766 ÷ 76? (a) 350 (b) 35 (c) 3500

Answer key

  1. 80
  2. 39
  3. 6.6
  4. 30
  5. 95
  6. 43
  7. 6.3
  8. 20
  9. 6.5
  10. 63
  11. 64
  12. 38
  13. 82
  14. 22
  15. 28
  16. 5.2
  17. 7.6
  18. 75
  19. 7.8
  20. 64
  21. 8.6
  22. 7.4
  23. 6.9
  24. 28
  25. 82
  26. 6.7
  27. 6.6
  28. 86
  29. 4.7
  30. 8.3
  31. 24
  32. 36
  33. 9.8
  34. 22
  35. 39
  36. 46
  37. 6.1
  38. 27
  39. 63
  40. 35

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