B7.1.1 · Strand 1, sub-strand 1

Number and Numeration Systems

Reading, writing, comparing and rounding very large numbers and decimals, and using significant figures.

1. Lesson 1 · B7.1.1.1.1 · about 45 min

   Modelling Numbers up to and beyond One Billion

   Ghana's national budget, the population of Africa and the money in our banks are all counted in billions. In this lesson you will see exactly how big one billion is, build large numbers with multi-base blocks, and make big cedi amounts with GH₵20, GH₵50, GH₵100 and GH₵200 notes.

2. Lesson 2 · B7.1.1.1.2 · about 45 min

   Comparing and Ordering Numbers beyond One Billion

   Which region has more people? Which year did Ghana earn more from cocoa? Which bank holds more money? To answer questions like these you must compare very big numbers quickly and correctly. In this lesson you will compare and order numbers beyond one billion, use the symbols >, < and =, skip count in 25s, 50s and 250s, and find numbers that are more or less than a given number.

3. Lesson 3 · B7.1.1.1.3 · about 45 min

   Rounding Large Whole Numbers and Significant Figures

   Newspapers say "Ghana has about 30.8 million people" instead of 30,832,019 because a rounded number is easier to read, remember and compare. In this lesson you will round very large whole numbers to the nearest ten, hundred, thousand, ten-thousand and hundred-thousand, learn the difference between rounding off, rounding up and rounding down, and express whole numbers to a given number of significant figures.

4. Lesson 4 · B7.1.1.1.4 · about 45 min

   Rounding Decimals to Tenths, Hundredths and Thousandths

   Fuel prices, exchange rates and science measurements often have many digits after the decimal point, but our money only goes down to the pesewa (one hundredth of a cedi). In this lesson you will round decimals to the nearest tenth, hundredth and thousandth, and learn how rounding up, rounding down and rounding off work with decimals.

5. Lesson 5 · B7.1.1.1.5 · about 50 min

   Significant Figures and Decimal Places

   A tape measure, a kitchen scale at Kejetia market and a thermometer at the clinic all give readings that are only accurate to a certain number of digits. Scientists, engineers and BECE examiners describe this accuracy using decimal places and significant figures. In this lesson you will learn which digits are significant (and when a zero counts), round decimals to a given number of decimal places or significant figures, and work out what an actual measurement could have been.