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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 822 · 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 3561 ÷ 76? (a) 4500 (b) 450 (c) 45
  2. 2.Best estimate of 3644 ÷ 76? (a) 460 (b) 46 (c) 4600
  3. 3.Best estimate of 1281 ÷ 42? (a) 320 (b) 32 (c) 3200
  4. 4.Best estimate of 2036 ÷ 31? (a) 6800 (b) 680 (c) 68
  5. 5.Best estimate of 4790 ÷ 52? (a) 9600 (b) 96 (c) 960
  6. 6.Best estimate of 1935 ÷ 57? (a) 320 (b) 32 (c) 3200
  7. 7.Best estimate of 4790 ÷ 56? (a) 800 (b) 80 (c) 8000
  8. 8.Best estimate of 3241 ÷ 84? (a) 4100 (b) 410 (c) 41
  9. 9.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.1
  10. 10.Best estimate of 7273 ÷ 82? (a) 9100 (b) 910 (c) 91
  11. 11.√89 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.5 (d) 9.6
  12. 12.Best estimate of 2090 ÷ 47? (a) 420 (b) 4200 (c) 42
  13. 13.√63 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.7 (d) 7.9
  14. 14.√80 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 9.2
  15. 15.Best estimate of 1314 ÷ 29? (a) 44 (b) 4400 (c) 440
  16. 16.Best estimate of 2392 ÷ 51? (a) 48 (b) 4800 (c) 480
  17. 17.√61 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 8.0 (d) 7.9
  18. 18.Best estimate of 2884 ÷ 66? (a) 4100 (b) 41 (c) 410
  19. 19.√23 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 4.7 (d) 4.9
  20. 20.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.9 (d) 6.8
  21. 21.√98 to 1 decimal place? (a) 10.0 (b) 10.1 (c) 9.9 (d) 10.2
  22. 22.Best estimate of 2840 ÷ 38? (a) 71 (b) 710 (c) 7100
  23. 23.Best estimate of 1081 ÷ 21? (a) 54 (b) 540 (c) 5400
  24. 24.Best estimate of 1470 ÷ 81? (a) 180 (b) 18 (c) 1800
  25. 25.Best estimate of 4430 ÷ 81? (a) 5500 (b) 550 (c) 55
  26. 26.√47 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 7.2
  27. 27.Best estimate of 291 ÷ 22? (a) 1500 (b) 15 (c) 150
  28. 28.Best estimate of 1296 ÷ 46? (a) 260 (b) 26 (c) 2600
  29. 29.√34 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.5
  30. 30.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  31. 31.Best estimate of 4708 ÷ 77? (a) 5900 (b) 590 (c) 59
  32. 32.√96 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.9 (d) 9.7
  33. 33.Best estimate of 735 ÷ 41? (a) 180 (b) 18 (c) 1800
  34. 34.√22 to 1 decimal place? (a) 4.7 (b) 5.0 (c) 4.8 (d) 4.9
  35. 35.Best estimate of 5580 ÷ 64? (a) 93 (b) 9300 (c) 930
  36. 36.Best estimate of 2582 ÷ 62? (a) 4300 (b) 43 (c) 430
  37. 37.Best estimate of 4556 ÷ 86? (a) 5100 (b) 510 (c) 51
  38. 38.Best estimate of 1852 ÷ 68? (a) 260 (b) 26 (c) 2600
  39. 39.Best estimate of 1452 ÷ 34? (a) 4800 (b) 48 (c) 480
  40. 40.Best estimate of 3777 ÷ 58? (a) 630 (b) 6300 (c) 63

Answer key

  1. 45
  2. 46
  3. 32
  4. 68
  5. 96
  6. 32
  7. 80
  8. 41
  9. 6.3
  10. 91
  11. 9.4
  12. 42
  13. 7.9
  14. 8.9
  15. 44
  16. 48
  17. 7.8
  18. 41
  19. 4.8
  20. 6.6
  21. 9.9
  22. 71
  23. 54
  24. 18
  25. 55
  26. 6.9
  27. 15
  28. 26
  29. 5.8
  30. 8.3
  31. 59
  32. 9.8
  33. 18
  34. 4.7
  35. 93
  36. 43
  37. 51
  38. 26
  39. 48
  40. 63

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