Rounding

• What is the purpose of rounding numbers in calculations?

  To make an estimate easier to compute
• What is the rounded estimate of 4521?

  5000
• What is the rounded estimate of 6111?

  6000
• What is the rounded estimate of 2944?

  3000
• What is the rounded estimate of 8413?

  8000
• What is the rounded estimate of 5083?

  5000
• What is the rounded estimate of 3199?

  3000
• What is the rounded estimate of 11182?

  11000
• What is the first significant figure of a number?

  The first non-zero digit of that number
• What is the first significant figure of 0.00342?


  3
• What happens to digits after the first significant figure if it encounters a 5?

  All digits become 0
• What is the result of rounding 1408 to 2 significant figures?

  1400
• What should estimating by rounding to 1 significant figure achieve?

  Make calculations easy enough for mental math
• How would you estimate the calculation 2.3 x 375.6 + 72.48?

  2 x 400 + 70 = 870
• What is the estimated result of 21.351 rounded to 1 significant figure?

  20
• What is the estimated result of 8.702 rounded to 1 significant figure?

  9
• What is the estimated result of 21.7 x 8.7 rounded to 1 significant figure?

  20 x 10 = 200