Whole Numbers

1.0 Numbers · 1.1 Whole Numbers

Syllabus tag: Kenya CBC | Grade 6 Mathematics | Strand 1.0 Numbers | Sub-Strand 1.1 Whole Numbers (20 Lessons)

Lesson objectives

By the end of this topic, you will be able to:

Whole numbers are the counting numbers and zero. In Grade 6 we work with numbers up to millions.

a) Place value and total value

The place value is what a position is worth.

The total value is the digit multiplied by its place value.

Write big numbers in groups of three from the right. It makes them easy to read.

b) Reading and writing

Read from the left, group by group.

So 2 456 789 is two million, four hundred and fifty-six thousand, seven hundred and eighty-nine.

Say the group name after each group: million, then thousand. The last group needs no name.

c) Ordering numbers

To compare two numbers, first count their digits. More digits means a bigger number.

If they have the same number of digits, compare from the left. The first place where they differ decides it.

So 84 391 is bigger than 84 297. In the hundreds place, 3 beats 2.

d) Rounding to the nearest thousand

Look at the digit after the place you are rounding to.

If it is 5 or more, round up. If it is less than 5, round down.

All the digits after become zero.

e) Squares

To square a number, multiply it by itself.

Say 15² as "fifteen squared". It is 225, not 30. Squaring is not doubling.

f) Square roots

A square root goes the other way. It asks which number was squared.

Since 36 × 36 = 1296, the square root of 1296 is 36. We write √1296 = 36.

To find a square root, try a number and square it. If the answer is too big, try smaller. If too small, try bigger.

The largest we need is √10 000, which is 100.

g) Where this is used

Population counts run into millions. Money is rounded to sensible amounts. Square numbers appear whenever you find the area of a square.

Words to know

Place value — the position of a digit in a number (e.g. tens, thousands).
Total value — what a digit is actually worth, given its place value (digit × place value).
Period — a group of three digits in a number, separated by a comma (ones, thousands, millions).
Rounding — expressing a number to the nearest ten, hundred, thousand, etc.
Square — the result of multiplying a number by itself.
Square root — a number which, multiplied by itself, gives the original number.
Perfect square — a whole number that is the square of another whole number.

:::checkpoint Check yourself

Now try the exercises — they use the same kind of numbers and the same four skills: reading/writing, ordering, rounding, and squares/square roots.