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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 375 · 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 3272 ÷ 63? (a) 5500 (b) 55 (c) 550
  2. 2.Best estimate of 1629 ÷ 62? (a) 270 (b) 27 (c) 2700
  3. 3.Best estimate of 2385 ÷ 31? (a) 8000 (b) 800 (c) 80
  4. 4.√92 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  5. 5.Best estimate of 3650 ÷ 73? (a) 520 (b) 5200 (c) 52
  6. 6.Best estimate of 6389 ÷ 68? (a) 91 (b) 910 (c) 9100
  7. 7.√24 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.7 (d) 4.9
  8. 8.√30 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.3
  9. 9.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.5
  10. 10.Best estimate of 1695 ÷ 43? (a) 4200 (b) 420 (c) 42
  11. 11.Best estimate of 1847 ÷ 26? (a) 6200 (b) 62 (c) 620
  12. 12.√58 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.9 (d) 7.7
  13. 13.√45 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.8
  14. 14.√48 to 1 decimal place? (a) 7.0 (b) 6.7 (c) 6.8 (d) 6.9
  15. 15.Best estimate of 6856 ÷ 74? (a) 9800 (b) 980 (c) 98
  16. 16.√34 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.9 (d) 6.0
  17. 17.Best estimate of 1774 ÷ 26? (a) 59 (b) 590 (c) 5900
  18. 18.√85 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.5 (d) 9.3
  19. 19.Best estimate of 2973 ÷ 44? (a) 740 (b) 74 (c) 7400
  20. 20.Best estimate of 965 ÷ 31? (a) 32 (b) 320 (c) 3200
  21. 21.√27 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 5.2 (d) 5.3
  22. 22.√22 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 4.9 (d) 4.7
  23. 23.√98 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 10.1 (d) 9.8
  24. 24.Best estimate of 5303 ÷ 62? (a) 8800 (b) 880 (c) 88
  25. 25.Best estimate of 2632 ÷ 32? (a) 88 (b) 880 (c) 8800
  26. 26.Best estimate of 3417 ÷ 38? (a) 850 (b) 8500 (c) 85
  27. 27.Best estimate of 4056 ÷ 53? (a) 81 (b) 8100 (c) 810
  28. 28.Best estimate of 4308 ÷ 54? (a) 860 (b) 86 (c) 8600
  29. 29.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  30. 30.√80 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.1 (d) 9.0
  31. 31.Best estimate of 1219 ÷ 56? (a) 2000 (b) 20 (c) 200
  32. 32.Best estimate of 1666 ÷ 44? (a) 420 (b) 4200 (c) 42
  33. 33.√26 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.1 (d) 4.9
  34. 34.√75 to 1 decimal place? (a) 8.4 (b) 8.7 (c) 8.5 (d) 8.6
  35. 35.√86 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.0 (d) 9.1
  36. 36.Best estimate of 2735 ÷ 32? (a) 9100 (b) 910 (c) 91
  37. 37.√44 to 1 decimal place? (a) 6.6 (b) 6.9 (c) 6.7 (d) 6.8
  38. 38.Best estimate of 4700 ÷ 49? (a) 9400 (b) 940 (c) 94
  39. 39.Best estimate of 1740 ÷ 69? (a) 250 (b) 2500 (c) 25
  40. 40.Best estimate of 1251 ÷ 21? (a) 63 (b) 630 (c) 6300

Answer key

  1. 55
  2. 27
  3. 80
  4. 9.6
  5. 52
  6. 91
  7. 4.9
  8. 5.5
  9. 8.6
  10. 42
  11. 62
  12. 7.6
  13. 6.7
  14. 6.9
  15. 98
  16. 5.8
  17. 59
  18. 9.2
  19. 74
  20. 32
  21. 5.2
  22. 4.7
  23. 9.9
  24. 88
  25. 88
  26. 85
  27. 81
  28. 86
  29. 9.7
  30. 8.9
  31. 20
  32. 42
  33. 5.1
  34. 8.7
  35. 9.3
  36. 91
  37. 6.6
  38. 94
  39. 25
  40. 63

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