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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 27 · 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.√28 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.2 (d) 5.1
  2. 2.Best estimate of 1456 ÷ 24? (a) 7300 (b) 73 (c) 730
  3. 3.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.8 (d) 4.9
  4. 4.Best estimate of 2268 ÷ 42? (a) 570 (b) 57 (c) 5700
  5. 5.√20 to 1 decimal place? (a) 4.6 (b) 4.4 (c) 4.5 (d) 4.3
  6. 6.Best estimate of 5118 ÷ 69? (a) 7300 (b) 73 (c) 730
  7. 7.Best estimate of 557 ÷ 26? (a) 1900 (b) 190 (c) 19
  8. 8.Best estimate of 890 ÷ 68? (a) 13 (b) 130 (c) 1300
  9. 9.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  10. 10.√22 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.7 (d) 4.5
  11. 11.√44 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.5 (d) 6.4
  12. 12.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  13. 13.√69 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 8.3
  14. 14.Best estimate of 3380 ÷ 66? (a) 4800 (b) 480 (c) 48
  15. 15.√38 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.0 (d) 5.9
  16. 16.Best estimate of 433 ÷ 21? (a) 22 (b) 2200 (c) 220
  17. 17.√34 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.9 (d) 6.0
  18. 18.Best estimate of 2088 ÷ 63? (a) 3500 (b) 35 (c) 350
  19. 19.Best estimate of 1758 ÷ 32? (a) 5900 (b) 59 (c) 590
  20. 20.Best estimate of 3606 ÷ 68? (a) 5200 (b) 52 (c) 520
  21. 21.√89 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.4 (d) 9.5
  22. 22.√85 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.2 (d) 9.1
  23. 23.√80 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 8.9
  24. 24.√92 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.3
  25. 25.Best estimate of 3441 ÷ 54? (a) 69 (b) 6900 (c) 690
  26. 26.Best estimate of 2521 ÷ 29? (a) 840 (b) 84 (c) 8400
  27. 27.Best estimate of 2062 ÷ 51? (a) 41 (b) 4100 (c) 410
  28. 28.√41 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.6 (d) 6.3
  29. 29.√53 to 1 decimal place? (a) 7.4 (b) 7.1 (c) 7.2 (d) 7.3
  30. 30.√72 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.5
  31. 31.Best estimate of 1952 ÷ 43? (a) 4900 (b) 490 (c) 49
  32. 32.Best estimate of 1967 ÷ 24? (a) 9800 (b) 980 (c) 98
  33. 33.√96 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.7 (d) 9.8
  34. 34.√61 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.8 (d) 7.9
  35. 35.Best estimate of 851 ÷ 23? (a) 4300 (b) 43 (c) 430
  36. 36.Best estimate of 563 ÷ 42? (a) 140 (b) 1400 (c) 14
  37. 37.Best estimate of 1476 ÷ 78? (a) 1800 (b) 18 (c) 180
  38. 38.√48 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.8 (d) 6.6
  39. 39.Best estimate of 1519 ÷ 31? (a) 5100 (b) 510 (c) 51
  40. 40.Best estimate of 476 ÷ 32? (a) 16 (b) 1600 (c) 160

Answer key

  1. 5.3
  2. 73
  3. 5.1
  4. 57
  5. 4.5
  6. 73
  7. 19
  8. 13
  9. 9.9
  10. 4.7
  11. 6.6
  12. 7.6
  13. 8.3
  14. 48
  15. 6.2
  16. 22
  17. 5.8
  18. 35
  19. 59
  20. 52
  21. 9.4
  22. 9.2
  23. 8.9
  24. 9.6
  25. 69
  26. 84
  27. 41
  28. 6.4
  29. 7.3
  30. 8.5
  31. 49
  32. 98
  33. 9.8
  34. 7.8
  35. 43
  36. 14
  37. 18
  38. 6.9
  39. 51
  40. 16

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