Level 1 · Ages 6–8
Read it again any time, including while you work through the exercises.
Imagine you are tidying up marbles. One marble on its own is a one, a single unit. When you have 10 of them, you put them in a bag: that is a ten. And when you have 10 bags, you store them in a box: that is a hundred, which means 100 marbles!
Thanks to this system, we can write every number with only ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. The secret is the place of each digit. In 347, the 3 counts as 3 hundreds (300 marbles), the 4 as 4 tens (40 marbles) and the 7 as 7 ones. We say that 347 = 300 + 40 + 7.
Watch out for the zero trap! In 305, the 0 says there are no tens, but it is very important: without it, we would read 35. The zero holds the place so every digit stays in the right spot.
In this lesson, you will learn to read, write and break apart every number up to 1000. It is the key that opens the door to all big calculations. Your turn to play!
Break the number 347 into hundreds, tens and ones.
347 = 3.. + 4. + 7
I look at the place of each digit: the 3 sits in the hundreds place, the 4 in the tens place, the 7 in the ones place.
3 centaines = 300
3 boxes of 100 marbles make 300 marbles.
4 dizaines = 40
4 bags of 10 marbles make 40 marbles.
300 + 40 + 7 = 347
I put everything together: 300 plus 40 plus 7, and I get 347 back.
Result: 347 = 3 hundreds + 4 tens + 7 ones = 300 + 40 + 7
Write as a number: 6 hundreds, 0 tens and 8 ones.
6 centaines = 600
I start with the hundreds: 6 hundreds is 600.
0 dizaine = 0
There are no tens, but I must write a 0 to hold the tens place.
600 + 0 + 8 = 608
I add the 8 ones: the number is 608, and definitely not 68!
Result: 6 hundreds, 0 tens and 8 ones is 608.