56
Exact and approximate values
Textbook: Part 2, lesson 56, pp. 54–56
GoalTell exact values from approximate values.
New words
exact value · aniq qiymatapproximate value · taqribiy qiymatcounting · sanashmeasuring · o‘lchash
Explanation
The result of counting is exact: there are 28 pupils in the class. The result of measuring is often approximate: if a pencil is 7 cm 4 mm long, in whole centimetres we say it is about 7 cm. Saying the distance is “about 300 km” is also an approximate value. An approximate value is close to the exact one but may not be equal to it.
Worked examples
120 seats were counted in the hall: an exact value.
Toshkent–Samarqand is about 300 km: an approximate value.
Class activity
“Exact or approximate?”: children count the chairs in the class and measure the room’s length in steps, then discuss which result is exact.
Practice
1
120 seats were counted in a hall. Is this an exact or an approximate value?
Exact
2
“Toshkent–Samarqand is about 300 km.” Is this an exact or an approximate value?
Approximate
3
A pencil measures 7 cm 4 mm on a ruler. What is its approximate length in whole centimetres?
7 cm
4
1 kg of bread costs 1 800 sum. How many sum do 3 kg cost? This is an exact value.
5400