Chapter 3: Double Century

Have you watched a cricket match where a batter scored 200 runs? That is called a double century. In this chapter, we travel from 100 to 200 , slowly, then by leaps and bounds.

What we'll learn

• Read and write numbers from 100 to 200.
• See how hundreds, tens and ones build a number.
• Skip count by 2s, 5s and 10s.
• Spot patterns in a number chart.
• Compare two numbers up to 200.

The big idea

A hundred is a big bundle , ten groups of ten. Picture ten chains of ten marigolds: that is one hundred flowers. When we go past 100, we are adding more tens and ones to that bundle. 145 means 1 hundred, 4 tens and 5 ones.

If we line up numbers from 100 to 200 in a chart with 10 columns, beautiful patterns appear. Going down a column, the tens digit grows by 1. Going across a row, the ones digit grows by 1.

Skip counting is a fast way to climb. Counting by 2s: 2, 4, 6, 8 , like climbing two stairs at a time. Counting by 5s helps us read clock minutes. Counting by 10s feels like flying.

Each number has its own spot on the number line , no number can borrow another's seat. That is why 132 is different from 123, even though the same digits are used.

Let's explore

Hundred chart. On paper, write numbers from 100 to 199 in rows of ten. Colour all the numbers that end in 5. What pattern do you see?

Cricket commentary. Pretend you are a commentator. Start at 100 and count by 1s up to 120, as if the batter is scoring one run at a time. Now count by 4s.

Bus number hunt. When you go out, note down any number you see that is bigger than 100 , bus numbers, house numbers, prices. List 5 of them. Order them from smallest to largest.

Beads of a hundred. Take a string of 100 beads (or imagine one). Add 27 more beads. What number is it now? Add 50 more. Now?

Worked examples

Example 1. Write the number that has 1 hundred, 6 tens and 3 ones.

• 1 hundred = 100.
• 6 tens = 60.
• 3 ones = 3.
• 100 + 60 + 3 = 163.

Example 2. Skip count by 5s from 130 up to 160.

• 130, 135, 140, 145, 150, 155, 160.

Example 3. Which is bigger: 174 or 147?

• Both have 1 hundred.
• 174 has 7 tens; 147 has 4 tens.
• 7 tens is more, so 174 is bigger.

Quick check

1. Write the number name for 128.
2. Skip count by 10s from 100 to 200.
3. How many tens are there in 150?
4. Which is smaller: 109 or 119?
5. A shopkeeper has 175 oranges. He sells 25. How many are left?

Recap

• One hundred is ten tens bundled together.
• Numbers up to 200 are made of hundreds, tens and ones.
• Skip counting helps us reach big numbers quickly and find patterns.