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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 328 · 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 400 ÷ 24? (a) 20 (b) 200 (c) 2000
  2. 2.Best estimate of 551 ÷ 21? (a) 2800 (b) 280 (c) 28
  3. 3.Best estimate of 761 ÷ 26? (a) 250 (b) 2500 (c) 25
  4. 4.Best estimate of 3125 ÷ 83? (a) 39 (b) 390 (c) 3900
  5. 5.√61 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.9 (d) 7.8
  6. 6.√59 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.7
  7. 7.Best estimate of 1676 ÷ 26? (a) 56 (b) 5600 (c) 560
  8. 8.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  9. 9.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.0
  10. 10.Best estimate of 1532 ÷ 52? (a) 3100 (b) 31 (c) 310
  11. 11.√75 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.8
  12. 12.Best estimate of 1430 ÷ 72? (a) 200 (b) 2000 (c) 20
  13. 13.Best estimate of 3821 ÷ 56? (a) 6400 (b) 64 (c) 640
  14. 14.√65 to 1 decimal place? (a) 7.9 (b) 8.2 (c) 8.1 (d) 8.0
  15. 15.Best estimate of 3187 ÷ 53? (a) 64 (b) 640 (c) 6400
  16. 16.Best estimate of 2268 ÷ 76? (a) 2800 (b) 28 (c) 280
  17. 17.Best estimate of 4345 ÷ 66? (a) 62 (b) 620 (c) 6200
  18. 18.Best estimate of 550 ÷ 28? (a) 1800 (b) 180 (c) 18
  19. 19.Best estimate of 5993 ÷ 73? (a) 860 (b) 8600 (c) 86
  20. 20.Best estimate of 2599 ÷ 78? (a) 320 (b) 3200 (c) 32
  21. 21.Best estimate of 2736 ÷ 69? (a) 3900 (b) 390 (c) 39
  22. 22.√62 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.9 (d) 7.8
  23. 23.√92 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.4
  24. 24.Best estimate of 2651 ÷ 41? (a) 6600 (b) 660 (c) 66
  25. 25.Best estimate of 1327 ÷ 22? (a) 6600 (b) 660 (c) 66
  26. 26.√87 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.5
  27. 27.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.3 (d) 6.2
  28. 28.Best estimate of 3615 ÷ 56? (a) 6000 (b) 600 (c) 60
  29. 29.Best estimate of 2190 ÷ 37? (a) 550 (b) 55 (c) 5500
  30. 30.√86 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.4
  31. 31.√51 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.1 (d) 7.0
  32. 32.Best estimate of 1110 ÷ 56? (a) 1900 (b) 190 (c) 19
  33. 33.Best estimate of 1284 ÷ 56? (a) 210 (b) 2100 (c) 21
  34. 34.√22 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.7 (d) 4.9
  35. 35.√70 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  36. 36.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 4.8
  37. 37.Best estimate of 4645 ÷ 81? (a) 580 (b) 58 (c) 5800
  38. 38.√79 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.9 (d) 8.8
  39. 39.Best estimate of 2871 ÷ 42? (a) 720 (b) 72 (c) 7200
  40. 40.Best estimate of 875 ÷ 29? (a) 2900 (b) 29 (c) 290

Answer key

  1. 20
  2. 28
  3. 25
  4. 39
  5. 7.8
  6. 7.7
  7. 56
  8. 6.1
  9. 7.1
  10. 31
  11. 8.7
  12. 20
  13. 64
  14. 8.1
  15. 64
  16. 28
  17. 62
  18. 18
  19. 86
  20. 32
  21. 39
  22. 7.9
  23. 9.6
  24. 66
  25. 66
  26. 9.3
  27. 6.3
  28. 60
  29. 55
  30. 9.3
  31. 7.1
  32. 19
  33. 21
  34. 4.7
  35. 8.4
  36. 5.1
  37. 58
  38. 8.9
  39. 72
  40. 29

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