Grade 4 · Unit 1: Number and place value

Large numbers and lakh

How do we read 1,00,000 and 100 000?

Dhaka is one of the most crowded cities in the world.

Counting people

Bangladesh has about 17 crore people. Big numbers like this need more places. Today we read numbers to 100 000 and learn lakh and crore.

Ten thousands

Each place is 10 times the place to its right. The 4 in 47 285 is worth 40 000. Read it: forty-seven thousand, two hundred and eighty-five.

Two ways to write big numbers

Internationally, digits are grouped in threes: 250 000. In Bangladesh, after the thousands, digits are grouped in twos: 2,50,000. Both show the same number.

Comparing and rounding

To compare, start with the biggest place. To round to the nearest 1000, look at the hundreds digit. 47 285 → 47 000. To the nearest 10 000 → 50 000.

Millions

A million is 1 000 000 – ten lakh. 3 450 000 has seven digits. International: 3 million 450 thousand. South Asian: 34 lakh 50 thousand. Dhaka has more than 1 crore people – over 10 million.

Roman numerals

The Romans used letters for numbers: I = 1, V = 5, X = 10, L = 50. Add when a smaller letter comes after: VI = 6, XV = 15. Subtract when it comes before: IV = 4, IX = 9, XL = 40.

What I learnt