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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 207 · 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 1030 ÷ 73? (a) 1500 (b) 15 (c) 150
  2. 2.Best estimate of 3222 ÷ 44? (a) 8100 (b) 810 (c) 81
  3. 3.Best estimate of 3195 ÷ 47? (a) 64 (b) 640 (c) 6400
  4. 4.Best estimate of 1524 ÷ 62? (a) 2500 (b) 25 (c) 250
  5. 5.√32 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.6 (d) 5.7
  6. 6.Best estimate of 3448 ÷ 43? (a) 8600 (b) 860 (c) 86
  7. 7.Best estimate of 812 ÷ 36? (a) 200 (b) 2000 (c) 20
  8. 8.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 6.0 (d) 5.8
  9. 9.Best estimate of 4349 ÷ 81? (a) 54 (b) 540 (c) 5400
  10. 10.Best estimate of 2938 ÷ 74? (a) 4200 (b) 42 (c) 420
  11. 11.Best estimate of 3490 ÷ 66? (a) 50 (b) 5000 (c) 500
  12. 12.√65 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.2 (d) 8.1
  13. 13.√96 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.8 (d) 10.1
  14. 14.Best estimate of 1155 ÷ 47? (a) 2300 (b) 230 (c) 23
  15. 15.√77 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.8
  16. 16.Best estimate of 2091 ÷ 72? (a) 300 (b) 30 (c) 3000
  17. 17.Best estimate of 1123 ÷ 26? (a) 370 (b) 37 (c) 3700
  18. 18.Best estimate of 2688 ÷ 83? (a) 3400 (b) 340 (c) 34
  19. 19.Best estimate of 1108 ÷ 46? (a) 22 (b) 220 (c) 2200
  20. 20.Best estimate of 604 ÷ 24? (a) 300 (b) 30 (c) 3000
  21. 21.Best estimate of 919 ÷ 63? (a) 1500 (b) 15 (c) 150
  22. 22.Best estimate of 3007 ÷ 49? (a) 600 (b) 60 (c) 6000
  23. 23.Best estimate of 579 ÷ 26? (a) 190 (b) 19 (c) 1900
  24. 24.√22 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.4 (d) 4.6
  25. 25.Best estimate of 877 ÷ 42? (a) 220 (b) 2200 (c) 22
  26. 26.√24 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 5.1 (d) 4.9
  27. 27.Best estimate of 696 ÷ 27? (a) 23 (b) 2300 (c) 230
  28. 28.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.9 (d) 7.8
  29. 29.Best estimate of 2082 ÷ 23? (a) 1040 (b) 10400 (c) 104
  30. 30.Best estimate of 3445 ÷ 53? (a) 6900 (b) 690 (c) 69
  31. 31.Best estimate of 4581 ÷ 76? (a) 57 (b) 5700 (c) 570
  32. 32.Best estimate of 1503 ÷ 36? (a) 3800 (b) 38 (c) 380
  33. 33.Best estimate of 644 ÷ 21? (a) 3200 (b) 320 (c) 32
  34. 34.Best estimate of 1459 ÷ 71? (a) 210 (b) 21 (c) 2100
  35. 35.Best estimate of 2438 ÷ 34? (a) 810 (b) 81 (c) 8100
  36. 36.Best estimate of 537 ÷ 27? (a) 180 (b) 1800 (c) 18
  37. 37.Best estimate of 1478 ÷ 64? (a) 250 (b) 25 (c) 2500
  38. 38.Best estimate of 628 ÷ 34? (a) 21 (b) 210 (c) 2100
  39. 39.Best estimate of 3973 ÷ 71? (a) 57 (b) 5700 (c) 570
  40. 40.Best estimate of 1054 ÷ 42? (a) 26 (b) 2600 (c) 260

Answer key

  1. 15
  2. 81
  3. 64
  4. 25
  5. 5.7
  6. 86
  7. 20
  8. 5.8
  9. 54
  10. 42
  11. 50
  12. 8.1
  13. 9.8
  14. 23
  15. 8.8
  16. 30
  17. 37
  18. 34
  19. 22
  20. 30
  21. 15
  22. 60
  23. 19
  24. 4.7
  25. 22
  26. 4.9
  27. 23
  28. 7.6
  29. 104
  30. 69
  31. 57
  32. 38
  33. 32
  34. 21
  35. 81
  36. 18
  37. 25
  38. 21
  39. 57
  40. 26

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