Approximation To Significant Figures & Decimal Places JSS2 Mathematics Lesson Note

  APPROXIMATION AND ESTIMATION (SIGNIFICANT AND DECIMAL PLACES) 

SIGNIFICANT: TO ROUND OFF A NUMBER CHANGE 0,1,2,3,4 TO 0 WHILE 5,6,7,8,9 TO 1 AND ADD IT TO THE NEXT NUMBER

Example 1: round off 492.763 to (a) 3 s.f (b) 3 s.f (c) 2 d.p (d) 4 d.p

Solution:

(a). 492.763 = 49 (since the third number is 2 it has changed to zero)

(b). 492.763 = 493 (the 2 has changed to 3 because 7 has changed to 1 and been added to 2 to become 3)

(c).492.763 = 492.76 (in decimal point we count after the point).

(d). 492.763 = 492.7630(since the number is not upto 4d.p we add zero to it.)

Example 2: calculate the following and round your answer to the given degree of accuracy

(a). 576.175 + 20.82 (2 d.p)

(b). 8.52 x 0.0651 (3 s.f)

Solution:

(a). 576.173 + 20.82 = 596.99

596.99 = 596.99 (2 d.p)

(b). 8.52 * 0.0651 = 0.554652

0.554652 = 0.555(3s.f)