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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 338 · 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 7822 ÷ 84? (a) 9800 (b) 98 (c) 980
  2. 2.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.9 (d) 9.7
  3. 3.√65 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 8.1 (d) 7.9
  4. 4.Best estimate of 1541 ÷ 36? (a) 3900 (b) 39 (c) 390
  5. 5.√35 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.8 (d) 6.0
  6. 6.Best estimate of 1505 ÷ 76? (a) 1900 (b) 190 (c) 19
  7. 7.√41 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.5 (d) 6.4
  8. 8.√86 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 9.3
  9. 9.Best estimate of 1538 ÷ 56? (a) 2600 (b) 26 (c) 260
  10. 10.√55 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.4 (d) 7.3
  11. 11.Best estimate of 630 ÷ 32? (a) 210 (b) 2100 (c) 21
  12. 12.√87 to 1 decimal place? (a) 9.3 (b) 9.0 (c) 9.1 (d) 9.2
  13. 13.Best estimate of 2374 ÷ 42? (a) 59 (b) 5900 (c) 590
  14. 14.Best estimate of 3516 ÷ 57? (a) 590 (b) 59 (c) 5900
  15. 15.Best estimate of 1841 ÷ 81? (a) 2300 (b) 230 (c) 23
  16. 16.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.9 (d) 9.8
  17. 17.Best estimate of 1919 ÷ 22? (a) 9600 (b) 960 (c) 96
  18. 18.√20 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.3 (d) 4.6
  19. 19.√23 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.9 (d) 4.7
  20. 20.Best estimate of 1933 ÷ 62? (a) 3200 (b) 320 (c) 32
  21. 21.Best estimate of 738 ÷ 21? (a) 3700 (b) 37 (c) 370
  22. 22.Best estimate of 2225 ÷ 78? (a) 2800 (b) 28 (c) 280
  23. 23.Best estimate of 625 ÷ 52? (a) 13 (b) 1300 (c) 130
  24. 24.Best estimate of 1697 ÷ 46? (a) 3400 (b) 34 (c) 340
  25. 25.Best estimate of 1159 ÷ 31? (a) 390 (b) 39 (c) 3900
  26. 26.Best estimate of 2611 ÷ 33? (a) 8700 (b) 87 (c) 870
  27. 27.Best estimate of 2554 ÷ 89? (a) 280 (b) 2800 (c) 28
  28. 28.Best estimate of 1957 ÷ 28? (a) 650 (b) 6500 (c) 65
  29. 29.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.4
  30. 30.Best estimate of 772 ÷ 32? (a) 260 (b) 26 (c) 2600
  31. 31.Best estimate of 4048 ÷ 44? (a) 10100 (b) 101 (c) 1010
  32. 32.√51 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.1 (d) 7.2
  33. 33.√48 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  34. 34.Best estimate of 1579 ÷ 72? (a) 230 (b) 2300 (c) 23
  35. 35.√72 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.5 (d) 8.4
  36. 36.√80 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 9.1 (d) 8.9
  37. 37.Best estimate of 2818 ÷ 41? (a) 700 (b) 7000 (c) 70
  38. 38.Best estimate of 3727 ÷ 52? (a) 750 (b) 75 (c) 7500
  39. 39.Best estimate of 1511 ÷ 46? (a) 3000 (b) 30 (c) 300
  40. 40.Best estimate of 1974 ÷ 39? (a) 4900 (b) 49 (c) 490

Answer key

  1. 98
  2. 9.6
  3. 8.1
  4. 39
  5. 5.9
  6. 19
  7. 6.4
  8. 9.3
  9. 26
  10. 7.4
  11. 21
  12. 9.3
  13. 59
  14. 59
  15. 23
  16. 9.9
  17. 96
  18. 4.5
  19. 4.8
  20. 32
  21. 37
  22. 28
  23. 13
  24. 34
  25. 39
  26. 87
  27. 28
  28. 65
  29. 5.1
  30. 26
  31. 101
  32. 7.1
  33. 6.9
  34. 23
  35. 8.5
  36. 8.9
  37. 70
  38. 75
  39. 30
  40. 49

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