Estimation JSS1 Mathematics Lesson Note

Estimation may be explained as a rough or sensible guess for a value or calculation. Although the estimated value is not correct, it gives us an idea of what the correct answer should be.

The common units of length are;

• Kilometres (km)
• Metres (m)
• Centimetres (cm)
• Millimetres (mm).

The standard units of Mass are;

• Tonne
• Kilogram (kg)
• Gram (g). 

  The standard units of Capacity are;

• Litre (l)
• Centilitre (cl)
• Millilitre (ml)

It is important to be able to choose the most appropriate metric units of measurement to use.

Example: To measure distances less than a meter, smaller units such as millimeters (mm) and centimeters are used; to measure large distances, meters and kilometers (km) are used.

State the metric units of the length you would use to measure the following:

(a). Length of your classroom = meter (m)

(b). Length of your fingernail in millimeters (mm)

(c). Your height = centimeter (cm)

(d) Distance between Lagos and Kaduna = kilometers (km)

(e). the height of a building = meter (m)

SIGNIFICANT: TO ROUND OFF A NUMBER, CHANGE 0, 1, 2, 3, AND 4 TO 0, WHILE 5, 6, 7, 8, AND 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 = 490 (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 points, we count after the point).

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