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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 269 · 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.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.2 (d) 5.1
  2. 2.Best estimate of 4582 ÷ 62? (a) 760 (b) 7600 (c) 76
  3. 3.Best estimate of 1267 ÷ 52? (a) 25 (b) 250 (c) 2500
  4. 4.√69 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.5
  5. 5.Best estimate of 900 ÷ 39? (a) 230 (b) 23 (c) 2300
  6. 6.Best estimate of 5055 ÷ 77? (a) 630 (b) 6300 (c) 63
  7. 7.Best estimate of 4079 ÷ 66? (a) 58 (b) 580 (c) 5800
  8. 8.Best estimate of 639 ÷ 24? (a) 3200 (b) 320 (c) 32
  9. 9.√38 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.4 (d) 6.2
  10. 10.Best estimate of 3380 ÷ 36? (a) 850 (b) 8500 (c) 85
  11. 11.√98 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.8 (d) 9.6
  12. 12.√37 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 5.9 (d) 6.1
  13. 13.√47 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 7.0 (d) 7.1
  14. 14.Best estimate of 2263 ÷ 72? (a) 320 (b) 3200 (c) 32
  15. 15.Best estimate of 4044 ÷ 59? (a) 67 (b) 6700 (c) 670
  16. 16.Best estimate of 1066 ÷ 47? (a) 210 (b) 2100 (c) 21
  17. 17.√50 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.1 (d) 7.2
  18. 18.Best estimate of 1657 ÷ 78? (a) 210 (b) 2100 (c) 21
  19. 19.Best estimate of 2165 ÷ 57? (a) 360 (b) 36 (c) 3600
  20. 20.Best estimate of 1780 ÷ 67? (a) 2500 (b) 250 (c) 25
  21. 21.Best estimate of 2363 ÷ 38? (a) 59 (b) 5900 (c) 590
  22. 22.Best estimate of 1566 ÷ 38? (a) 3900 (b) 390 (c) 39
  23. 23.Best estimate of 6776 ÷ 71? (a) 97 (b) 9700 (c) 970
  24. 24.Best estimate of 2277 ÷ 39? (a) 5700 (b) 57 (c) 570
  25. 25.Best estimate of 1609 ÷ 51? (a) 32 (b) 320 (c) 3200
  26. 26.√30 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.5 (d) 5.2
  27. 27.Best estimate of 1807 ÷ 56? (a) 3000 (b) 300 (c) 30
  28. 28.Best estimate of 1199 ÷ 23? (a) 60 (b) 6000 (c) 600
  29. 29.Best estimate of 513 ÷ 21? (a) 260 (b) 2600 (c) 26
  30. 30.√61 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.8 (d) 7.7
  31. 31.√32 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.4
  32. 32.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.8
  33. 33.Best estimate of 5713 ÷ 83? (a) 71 (b) 710 (c) 7100
  34. 34.Best estimate of 3445 ÷ 42? (a) 8600 (b) 86 (c) 860
  35. 35.√70 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.4 (d) 8.3
  36. 36.Best estimate of 5988 ÷ 73? (a) 8600 (b) 860 (c) 86
  37. 37.Best estimate of 1001 ÷ 64? (a) 170 (b) 17 (c) 1700
  38. 38.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.4 (d) 5.5
  39. 39.√62 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.7 (d) 7.8
  40. 40.√24 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 5.2 (d) 4.9

Answer key

  1. 5.1
  2. 76
  3. 25
  4. 8.3
  5. 23
  6. 63
  7. 58
  8. 32
  9. 6.2
  10. 85
  11. 9.9
  12. 6.1
  13. 6.9
  14. 32
  15. 67
  16. 21
  17. 7.1
  18. 21
  19. 36
  20. 25
  21. 59
  22. 39
  23. 97
  24. 57
  25. 32
  26. 5.5
  27. 30
  28. 60
  29. 26
  30. 7.8
  31. 5.7
  32. 9.6
  33. 71
  34. 86
  35. 8.4
  36. 86
  37. 17
  38. 5.6
  39. 7.9
  40. 4.9

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