Page 64 - ICSE Math 1

Number
4 Numbers from 10 to 20s from 10 to 20

Learning Outcomes

Students will be able to learn:
 the concept of tens and ones.
 to compare 2-digit numbers up to 20.
 to identify numbers before, after and in between the given numbers.
 the backward counting from 20.
 to order 2-digit numbers up to 20.
Concept of Tens and Ones

We know numbers from 1 to 9. We use ones place to write any number from
1 to 9.

1 = 1 one

2 = 2 ones

3 = 3 ones

4 = 4 ones

5 = 5 ones

6 = 6 ones

7 = 7 ones

8 = 8 ones

9 = 9 ones

To write numbers further, we need two H T O
places—tens and ones.

We can count 2-digit numbers on an abacus by
using rods T and O.
Rod O reads in ones. Rod T reads in tens.

We can put a maximum of 9 beads in each rod.
Let’s count further. 9 beads in rod O show 9 ones or 9.

54