Estimation

• What is the first significant figure of the number 1566?


  1
• What is the first significant figure of the number 55460?


  5
• What is the first significant figure of the number 2000?


  2
• What is the first significant figure of the number 5000?


  5
• What is the first significant figure of the number 336644?


  3
• What is the first significant figure of the number 300G?


  3
• What is the first significant figure of the number 0.2?


  2
• What is the first significant figure of the number 0.00454?


  4
• What is the first significant figure of the number 0.005?


  5
• What is the first significant figure of the number 100987?


  1
• What is the first significant figure of the number 0.1?


  1
• What is the first significant figure of the number 91-64?


  9
• What is the first significant figure of the number 2?


  2
• What is the first significant figure of the number 1600?


  1
• What is the first significant figure of the number 5500?


  5
• When a question says ‘estimate’ or ‘approximate‘ you are expected to round the numbers to 1 significant figure
• E.g. Estimate

  4.5 x 9.6

  =5 x 10 (rounded to 1 sf)

  = 50
• When do we not need to round figures in estimation with roots?


  When estimating square roots
• What is the approximate value of $\sqrt{3}$?


  2
• What is the approximate value of $\sqrt{94}$?


  9
• What is the approximate value of $\sqrt{110}$?


  10
• What is the approximate value of $\sqrt{2}$?


  1
• What is the approximate value of $\sqrt{8}$?


  3
• What is the approximate value of $\sqrt{10}$?


  3
• What is the approximate value of $\sqrt{15}$?


  4
• What is the approximate value of $\sqrt{26}$?


  5
• What is the approximate value of $\sqrt{32}$?


  6
• What is the approximate value of $\sqrt{45}$?


  7
• What is the approximate value of $\sqrt{70}$?


  8
• How can you estimate $\sqrt{2.03} \times 0.041$?


  $\sqrt{2} \times 0.05 \times 40 \approx 6 \times 4$
• What is the estimated value of $\sqrt{36700} \div 50$?


  7
• What is the estimated value of $7.79 +$$5$?


  12.79