Understanding measurement

To convert from a larger unit to a smaller unit you multiply the measurement by the correct multiple of ten.

To convert from a smaller unit to a larger unit you divide the measurement by the correct multiple of 10.

Area is always measured in square units. To convert areas from unit to another you need to square the appropriate length conversion factor.

Volume is measured in cubic units. To convert volumes from one unit to another you need to cube the appropriate length conversion factor.

Time is not decimal. 1 h 15 means one hour and 15/60 (or 1/4) of an hour, not 1.15 h.

One hour and 15 minutes is written as 1:15.

Time can be written using a.m. and p.m. notation or as 24-hour time using the numbers from 0 to 24 to give times from 12 midnight on one day (00:00 h) to one second before midnight (23:59:59).

Even in the 24-hour clock system, time is not decimal. The time one minute after 15:59 is 16:00.

All measurements we make are rounded to some degree of accuracy. The degree of accuracy allows you to work out the highest and lowest possible value of the measurements.

The highest possible value is called the upper bound and lowest possible value is called the lower bound.

When you work with more than one rounded value you need to use upper and lower bounds of each.

Conversion graphs allow you to convert from one unit of measurement to another by providing the value of both units on different axes. To find one value(x) when the other (y) is given, you need to find the y-value against the graph and then read off the corresponding value on the other axis.

When you change money from one currency to another you so at a given rate of exchange. Changing to another currency os called buying foreign currency.

Exchange rates can be worked out using conversion graphs, but more often, they are worked out by doing calculations.

Doing calculations with money is just like doing calculations with decimals but you need to remember to include the currency symbols in your answers.