Approximation.

Mathematics for Jss 1 2^nd Term.

Theme: Basic Operations.

Week 3 and 4.

Approximation.

Performance Objectives.

Students should be able to

1. Approximate answers to addition and subtraction of problems to a given accuracy.
2. 2. Approximate answers to multiplication and division problems to a given degree of accuracy.

    3 .Round numbers to the nearest 10,100,1000.

    4. Apply approximation to basic operations in day to day activities.

    5. Solve quantitative questions on approximation.

Content.

Approximation is a way of using rounded numbers to estimate answers to calculation.

Example 1: Work out 47+21 to the nearest 10.

47=50

21=20

50+20

=70

Rule for Approximation.

Numbers from 0-4 are rounded down to zero

Numbers from 5-9 are rounded up to 1.

Example 2. Round up 6754 to the nearest thousand

6754=7000.

1.        C)46250  D)45520

Week 4.

Approximation can help decide whether an answer to calculation is right or not. To find an approximate answer to a calculation we round the answers to easy numbers usually 1sf or 2sf or to the nearest whole number. then work out the approximated answer.

Example1: A woman decides to buy a bed costing Ꞥ8950 and a table costingꞤ3680.Using approximation estimate the total amount she decides to spend. And the actual cost.

Answer: Estimated cost

 bed Ꞥ8950 to nearest whole number=Ꞥ9000

            Table Ꞥ3680 to the nearest whole number=Ꞥ4000

Ꞥ9000+Ꞥ4000=Ꞥ13000.

Actual cost

 Bed=Ꞥ8950

+table Ꞥ3680

=Ꞥ12630.

Example 2: A box full of exercise books weigh 12kg.If one exercise book weighs 10.2g.Find the approximate number of exercise books in the box.

Answer:

A box=12kg to nearest whole number =10kg

1 exercise book to nearest whole number=10g

10kg=1000gx10

=10000

Therefore 10000/10

=1000 exercise books.